doc(release): draft for RELEASE NOTES

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

CHANGELOG.md

 # RELEASE NOTES: #
 
+## v1.2.0 -- September 2021 ##
+
+* Initial public release
+* NRF registration
+  - with FQDN DNS resolution
+* Proper mySQL DB deployment management
+* Full support for Ubuntu18 and RHEL8
+
 ## v1.0.0 -- July 2021 ##
 
-* Initial release
+* Initial private release