Add note to get_allowed_mime_types() about the upload_mimes filter. props JustinSainton. fixes #20990.

git-svn-id: http://core.svn.wordpress.org/trunk@21180 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -1756,7 +1756,7 @@ function wp_check_filetype_and_ext( $file, $filename, $mimes = null ) {
  * Retrieve list of allowed mime types and file extensions.
  *
  * @since 2.8.6
- *
+ * @uses apply_filters() Calls 'upload_mimes' on returned array
  * @return array Array of mime types keyed by the file extension regex corresponding to those types.
  */
 function get_allowed_mime_types() {