Add license info

CHANGELOG.md

+# RELEASE NOTES: #
+
+## v1.0.0 -- Jun 2021 ##
+
+* Initial release
+

CONTRIBUTING.md

+# Contributing to OpenAir-CN-5G #
+
+We want to make contributing to this project as easy and transparent as possible.
+
+Please refer to the steps described on our website: [How to contribute to OAI](https://www.openairinterface.org/?page_id=112)
+
+1. Sign and return a Contributor License Agreement to OAI team.
+2. Create an account on [Eurecom GiLab Server](https://gitlab.eurecom.fr/users/sign_in) if you do not have any.
+   - If your email domain (`@domain.com`) is not whitelisted, please contact us (mailto:contact@openairinterface.org).
+   - Eurecom GitLab does NOT accept public email domains.
+3. Provide the `username` of this account to the OAI team (mailto:contact@openairinterface.org) so you have developer rights on this repository.
+4. The policies are described in these wiki pages: [OAI Policies](https://gitlab.eurecom.fr/oai/openairinterface5g/wikis/oai-policies-home)
+   - You can fork onto another hosting system. But we will **NOT** accept a pull request from a forked repository.
+      * This decision was made for the license reasons.
+      * The Continuous Integration will reject your pull request.
+   - All pull requests SHALL have **`develop`** branch as target branch.
+
+## Coding Styles ##
+
+We are using `clang-format` as formatting tool on the C/C++ code.
+
+At the time of writing (March 30th, 2020), we are using `clang-format` version 8.0.0 or above. By default, on a Ubuntu bionic Desktop edition, you would install version 6.0.0.
+
+So it is very likely you will have to install it manually. Again, at the time of writing, the working version we found was 9.0.0.
+
+```bash
+$ wget https://releases.llvm.org/9.0.0/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz
+$ mkdir clang_tmp
+$ tar xvfJ  clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04.tar.xz -C ./clang_tmp
+$ sudo cp clang_tmp/clang+llvm-9.0.0-x86_64-linux-gnu-ubuntu-18.04/bin/clang-format /usr/bin/clang-format
+$ rm -Rf clang*
+$ clang-format --version
+clang-format version 9.0.0 (tags/RELEASE_900/final)
+```
+
+How to format:
+
+```bash
+$ cd myClonedWorkspace/src
+$ clang-format -i theFilesYouWantToFormat
+```
+
+## License ##
+
+By contributing to OpenAirInterface, you agree that your contributions will be licensed under the [LICENSE](LICENSE) file in the root directory of this source tree.
+
+## Continuous Integration process ##
+
+1.  You push your modified code with the new branch onto our [official GitLab repository](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-udm).
+    -  Please make the name of the branch explicit and short.
+2.  You create a pull request from the [dedicated web page](https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-udm/-/merge_requests).
+    -  The `target` (`base` in the web-page) branch **SHALL be `develop`**.
+    -  The `source` (`compare` in the web-page) branch is your branch.
+3.  Our Continuous Integration (CI) process will be triggered automatically on your proposed modified code and check the validity.
+    -  Check build
+    -  Check some formatting rules
+    -  Run a bunch of tests
+4.  If at least one of these steps fails, you will have to push corrections onto your source branch.
+    -  The step 3. will be again automatically triggered on this new commit.
+    -  Please wait that your run is finished before committing and pushing new modifications on your source branch.
+    -  That will allow fairness on the CI usage to other contributors.
+4.  When this automated process passes, one of our CI administrators will review your changes or assign a senior contributor
+  to do a peer-review.
+5.  Once the peer reviewer accepts your modification, one of our CI administrators will accept and merge your pull request
+    -  The CI will run again on the new `develop` branch commit.
+    -  The source branch WILL be deleted by one of our CI administrators.
+

LICENSE

+        The OpenAirInterface Software Alliance (OSA)
+          OAI Public License (Version 1.1)
+
+LICENSE TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION OF OPENAIR 5G SOFTWARE.
+
+1.  Definitions.
+
+“License” shall mean the terms and conditions for use, reproduction, and distribution set forth 
+in this document.
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+
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+November 2014.
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+3.3 Patent Litigation
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+add Your own attribution notices within Derivative Works that You distribute, alongside or as 
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+You may add Your own copyright statement to Your modifications and may provide 
+additional or different license terms and conditions for use, reproduction, or distribution of 
+Your modifications, or for any such Derivative Works as a whole, provided Your use, 
+reproduction, and distribution of the Work otherwise complies with the conditions stated in 
+this License.
+
+6. Submission of Contributions. 
+Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be 
+under the terms and conditions of this License, without any additional terms or conditions. 
+Notwithstanding the above, nothing herein shall supersede or modify the terms of any 
+separate license agreement such as the Contributor License Agreement You may have 
+executed with Licensor regarding such Contributions.
+
+7. Trademarks. 
+This License does not grant permission to use the trade names, trademarks, service marks, or 
+product names of the Licensor, except as required for reasonable and customary use in 
+describing the origin of the Work and reproducing the content of the NOTICE file.
+
+8. Disclaimer of Warranty. 
+Unless required by applicable law or agreed to in writing, Licensor provides the Work (and 
+each Contributor provides its Contributions) on an “AS IS” BASIS, WITHOUT 
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, 
+without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, 
+MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely 
+responsible for determining the appropriateness of using or redistributing the Work and 
+assume any risks associated with your exercise of permissions under this License.
+
+9. Limitation of Liability. 
+In no event and under no legal theory, whether in tort (including negligence), contract, or 
+otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or 
+agreed to in writing, shall Licensor and any Contributor, as such, be liable to You for 
+damages, including any direct, indirect, special, incidental, or consequential damages of any 
+character arising as a result of this License or out of Your use or inability to use the Work 
+(including but not limited to damages for loss of goodwill, work stoppage, computer failure or 
+malfunction, or any and all other commercial damages or losses), even if such Contributor has 
+been advised of the possibility of such damages.
+
+10. Accepting Warranty or Additional Liability. 
+While redistributing the Work or Derivative Works thereof, You may choose to offer, and 
+charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations 
+and/or rights consistent with this License. However, in accepting such obligations, You may 
+act only on Your own behalf and on Your sole responsibility, not on behalf of any other 
+Contributor and/or the Licensor, and only if You agree to indemnify, defend, and hold each 
+Contributor and/or the Licensor harmless for any liability incurred by, or claims asserted 
+against, such Contributor and/or Licensor by reason of Your accepting any such warranty or 
+additional liability.
+
+11. Applicable law. 
+The present license shall be governed by the laws of France.
+
+END OF TERMS AND CONDITIONS
+
+1.  APPENDIX: How to apply the PRESENT OPENAIR 5G License to your work
+To apply the present License to your work, attach the following boilerplate notice, with the 
+fields enclosed by brackets “[]” replaced with your own identifying information. (Don’t 
+include the brackets!) The text should be enclosed in the appropriate comment syntax for the 
+file format. We also recommend that a file or class name and description of purpose be 
+included on the same “printed page” as the copyright notice for easier identification within 
+third-party archives.
+
+Copyright [yyyy] [name of copyright owner]
+
+Licensed under the License terms and conditions for use, reproduction, and distribution of 
+OPENAIR 5G software (the “License”);
+
+you may not use this file except in compliance with the License. You may obtain a copy of 
+the License at
+
+Unless required by applicable law or agreed to in writing, software distributed under the 
+License is distributed on an “AS IS” BASIS,
+
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+
+See the License for the specific language governing permissions and limitations under the 
+License.
+

NOTICE

+UDR is distributed under OAI Public License (Version 1.1).
+
+However, it also includes third party-software indicated below.
+
+#To be updated
\ No newline at end of file