Cross reference `get_the_archive_title()` and `get_the_archive_description()` in the inline documentation for their corresponding template tags.

Also define the default values for `$before` and `$after` in the template tag documentation.

See [30223]. See #21995.


git-svn-id: https://develop.svn.wordpress.org/trunk@30224 602fd350-edb4-49c9-b593-d223f7449a82