Help: Update Sphinx versionadded directives for 4.0 release

Run the script:

    Utilities/Sphinx/update_versions.py --since v3.31.0 --overwrite

Manually renumber `3.32` to `4.0` since the script is meant for
minor version increments.  Also filter out changes to documents
that were added for long-existing variables.

Help/variable/CMAKE_LIST_FILE_NAME.rst

@@ -1,7 +1,7 @@
 CMAKE_LIST_FILE_NAME
 --------------------
 
- .. versionadded:: 4.0
+.. versionadded:: 4.0
 
 The name of the CMake project files. This determines the top-level file
 processed when CMake is configured, and the file processed by