Docs: Add missing parameter and return notations to the DocBlock for the deprecated `get_usernumposts()` function.

See #32246.


git-svn-id: https://develop.svn.wordpress.org/trunk@36030 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/deprecated.php

@@ -2412,11 +2412,14 @@ function get_profile( $field, $user = false ) {
 }
 
 /**
- * Number of posts user has written.
+ * Retrieves the number of posts a user has written.
  *
  * @since 0.71
  * @deprecated 3.0.0 Use count_user_posts()
  * @see count_user_posts()
+ *
+ * @param int $userid User to count posts for.
+ * @return int Number of posts the given user has written.
  */
 function get_usernumposts( $userid ) {
 	_deprecated_function( __FUNCTION__, '3.0', 'count_user_posts()' );