Add inline documentation for the `option_none_value` argument added to `wp_dropdown_users|categories()` in [28564].

Fixes #16625.


git-svn-id: https://develop.svn.wordpress.org/trunk@28570 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/category-template.php

@@ -292,6 +292,7 @@ function category_description( $category = 0 ) {
  * The list of arguments is below:
  *     'show_option_all' (string) - Text to display for showing all categories.
  *     'show_option_none' (string) - Text to display for showing no categories.
+ *     'option_none_value' (mixed) - Value to use when no category is selected.
  *     'orderby' (string) default is 'ID' - What column to use for ordering the
  * categories.
  *     'order' (string) default is 'ASC' - What direction to order categories.

src/wp-includes/user.php

@@ -1252,6 +1252,7 @@ function setup_userdata($for_user_id = '') {
  * <ol>
  * <li>show_option_all - Text to show all and whether HTML option exists.</li>
  * <li>show_option_none - Text for show none and whether HTML option exists.</li>
+ * <li>option_none_value - Value to use when no option is selected.</li>
  * <li>hide_if_only_one_author - Don't create the dropdown if there is only one user.</li>
  * <li>orderby - SQL order by clause for what order the users appear. Default is 'display_name'.</li>
  * <li>order - Default is 'ASC'. Can also be 'DESC'.</li>