Docs: Add missing `session_token_manager` duplicate hook reference in `wp-includes/class-wp-session-tokens.php`.

Props keesiemeijer.
See #39371.

git-svn-id: https://develop.svn.wordpress.org/trunk@39670 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-session-tokens.php

@@ -237,6 +237,7 @@ abstract class WP_Session_Tokens {
 	 * @static
 	 */
 	final public static function destroy_all_for_all_users() {
+		/** This filter is documented in wp-includes/class-wp-session-tokens.php */
 		$manager = apply_filters( 'session_token_manager', 'WP_User_Meta_Session_Tokens' );
 		call_user_func( array( $manager, 'drop_sessions' ) );
 	}