[X86] Add clang release notes for HRESET and minor change for llvm release notes. (NFC)

GitOrigin-RevId: e32036b9732fd1ec4794fef48ec79a268aa8cbce
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 540cf91..0e2915c 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -200,6 +200,8 @@
   implies -mtune=<cpu>. -mtune=generic is the default with no -march or -mtune
   specified.
 
+- Support for feature ``HRESET`` has been added.
+
 Internal API Changes
 --------------------