Add inline documentation for the `run_wptexturize` filter.

Props miqrogroove for the original patch.
Fixes #19550.

Built from https://develop.svn.wordpress.org/trunk@28723


git-svn-id: http://core.svn.wordpress.org/trunk@28537 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Improve inline documentation for the `wp_spaces_regexp` filter.

Fixes #27588.

Built from https://develop.svn.wordpress.org/trunk@28724


git-svn-id: http://core.svn.wordpress.org/trunk@28538 1a063a9b-81f0-0310-95a4-ce76da25c4cd