[Clang] Fix typo in ReleaseNotes.rst

Author: cor3ntin

clang/docs/ReleaseNotes.rst

@@ -112,7 +112,7 @@ C++2b Feature Support
 
 - Implemented `P2036R3: Change scope of lambda trailing-return-type <https://wg21.link/P2036R3>`_
   and `P2579R0 Mitigation strategies for P2036 <https://wg21.link/P2579R0>`_.
-  This proposals modify how variables captured in lambdas can appear in trailing return type
+  These proposals modify how variables captured in lambdas can appear in trailing return type
   expressions and how their types are deduced therein, in all C++ language versions.
 
 CUDA/HIP Language Changes in Clang