Put docs in the right place

Author: DaveBrantonCTCT

clang-tools-extra/docs/ReleaseNotes.rst

@@ -243,6 +243,10 @@ Changes in existing checks
   <clang-tidy/checks/readability/qualified-auto>` check by adding the option
   `IgnoreAliasing`, that allows not looking at underlying types of type aliases.
 
+- Improved :doc:`modernize-use-std-format 
+  <clang-tidy/checks/modernize/use-std-format>` now correctly replaces signed types, and correctly 
+  adds a ``static_cast`` to the underlying type when being printed in hex.
+
 Removed checks
 ^^^^^^^^^^^^^^
 

llvm/docs/ReleaseNotes.md

@@ -150,9 +150,6 @@ Changes to the Debug Info
 Changes to the LLVM tools
 ---------------------------------
 
-* modernize-use-std-format now correctly replaces signed types, and correctly 
-  adds a static_cast to the underlying type when being printed in hex.
-
 Changes to LLDB
 ---------------------------------