Reword licensing part

CONTRIBUTING.md

@@ -2,9 +2,9 @@ Contributing to {fmt}
 =====================
 
 By submitting a pull request or a patch, you represent that you have the right
-to license your contribution to the {fmt} project owners and the community, and
-agree that your contributions are licensed under the {fmt} license that may
-change in the future.
+to license your contribution to the {fmt} project owners and the community,
+agree that your contributions are licensed under the {fmt} license, and agree
+to future changes to the licensing.
 
 All C++ code must adhere to [Google C++ Style Guide](
 https://google.github.io/styleguide/cppguide.html) with the following