Add docs to the woefully under-documented `get_pages()`.

Props DrewAPicture.
Fixes #25186.



git-svn-id: https://develop.svn.wordpress.org/trunk@25266 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: further styling for medialement players, props iamtakashi. Fixes #25209.

git-svn-id: https://develop.svn.wordpress.org/trunk@25267 602fd350-edb4-49c9-b593-d223f7449a82