Help: Update Sphinx versionadded directives for 3.31 release

Run the script:

    Utilities/Sphinx/update_versions.py --since v3.30.0 --overwrite

Help/command/cmake_pkg_config.rst

@@ -1,6 +1,8 @@
 cmake_pkg_config
 ----------------
 
+.. versionadded:: 3.31
+
 .. only:: html
 
    .. contents::

Help/variable/CMAKE_LANG_CREATE_SHARED_LIBRARY_ARCHIVE.rst

@@ -1,6 +1,8 @@
 CMAKE_<LANG>_CREATE_SHARED_LIBRARY_ARCHIVE
 ------------------------------------------
 
+.. versionadded:: 3.31
+
 Rule variable to create a shared library with archive.
 
 This is a rule variable that tells CMake how to create a shared

Help/variable/CMAKE_SHARED_LIBRARY_ARCHIVE_SUFFIX.rst

@@ -1,6 +1,8 @@
 CMAKE_SHARED_LIBRARY_ARCHIVE_SUFFIX
 -----------------------------------
 
+.. versionadded:: 3.31
+
 The suffix for archived shared libraries that you link to.
 
 The suffix to use for the end of a archive containing a