[clang][docs] Redirect folks from CSA sections for usual Clang crashes (#175935)

Almost in every release there are contributors adding non-CSA entries to
the CSA release docs sections due to confusion.
To reduce the temptation in the future, let's add a reminder.

Note that it's not the end of the world if entries are put in the wrong
section, because I always moved them in the past. It would be simply
more convenient to avoid this.

clang/docs/ReleaseNotes.rst

@@ -216,17 +216,13 @@ Code Completion
 Static Analyzer
 ---------------
 
-New features
-^^^^^^^^^^^^
-
-Crash and bug fixes
-^^^^^^^^^^^^^^^^^^^
-
-Improvements
-^^^^^^^^^^^^
-
-Moved checkers
-^^^^^^^^^^^^^^
+.. comment:
+  This is for the Static Analyzer.
+  Using the caret `^^^` underlining for subsections:
+    - Crash and bug fixes
+    - New checkers and features
+    - Improvements
+    - Moved checkers
 
 .. _release-notes-sanitizers:
 

clang/docs/ReleaseNotesTemplate.txt

@@ -205,17 +205,13 @@ Code Completion
 Static Analyzer
 ---------------
 
-New features
-^^^^^^^^^^^^
-
-Crash and bug fixes
-^^^^^^^^^^^^^^^^^^^
-
-Improvements
-^^^^^^^^^^^^
-
-Moved checkers
-^^^^^^^^^^^^^^
+.. comment:
+  This is for the Static Analyzer.
+  Using the caret `^^^` underlining for subsections:
+    - Crash and bug fixes
+    - New checkers and features
+    - Improvements
+    - Moved checkers
 
 .. _release-notes-sanitizers: