Docs: Add missing `@return` tag for `wp_xmlrpc_server::_is_greater_than_one()`.

Props ankitmaru.
Fixes #51465.

git-svn-id: https://develop.svn.wordpress.org/trunk@49098 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-xmlrpc-server.php

@@ -1307,6 +1307,7 @@ class wp_xmlrpc_server extends IXR_Server {
 	 * @since 3.4.0
 	 *
 	 * @param int $count Number to compare to one.
+	 * @return bool True if the number is greater than one, false otherwise.
 	 */
 	private function _is_greater_than_one( $count ) {
 		return $count > 1;