Update ReleaseNotes.md

Author: mcbarton

docs/ReleaseNotes.md

@@ -16,7 +16,7 @@ interoperability on the fly. In such scenarios CppInterOp can be used to provide
 the necessary introspection information to the other side helping the language
 cross talk.
 
-# What's New in CppInterOp 1.5.0?
+## What's New in CppInterOp 1.5.0?
 
 Some of the major new features and improvements to CppInterOp are listed here.
 Generic improvements to CppInterOp as a whole or to its underlying
@@ -51,7 +51,7 @@ infrastructure are described first.
  git log v1.4.0..main | grep 'Fixes|Closes'
  --->
 
-# Special Kudos
+## Special Kudos
 
 This release wouldn't have happened without the efforts of our contributors,
 listed in the form of Firstname Lastname (#contributions):