[NFC] Fix typo in ReleaseNotes.rst (#82655)

Deletes the leading 7 from the textual issue number.

clang/docs/ReleaseNotes.rst

@@ -270,7 +270,7 @@ Bug Fixes to C++ Support
   local variable, which is supported as a C11 extension in C++. Previously, it
   was only accepted at namespace scope but not at local function scope.
 - Clang no longer tries to call consteval constructors at runtime when they appear in a member initializer.
-  (`#782154 <https://github.com/llvm/llvm-project/issues/82154>`_`)
+  (`#82154 <https://github.com/llvm/llvm-project/issues/82154>`_`)
 - Fix crash when using an immediate-escalated function at global scope.
   (`#82258 <https://github.com/llvm/llvm-project/issues/82258>`_)
 - Correctly immediate-escalate lambda conversion functions.