Menus: Add `social` as tertiary mapping group

Allows mapping of all social menus that include the term `social` in their slug.

See #39692.


git-svn-id: https://develop.svn.wordpress.org/trunk@41801 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/nav-menu.php

@@ -1119,6 +1119,7 @@ function wp_map_nav_menu_locations( $new_nav_menu_locations, $old_nav_menu_locat
 	$common_slug_groups = array(
 		array( 'header', 'main', 'navigation', 'primary', 'top' ),
 		array( 'bottom', 'footer', 'secondary', 'subsidiary' ),
+		array( 'social' ),
 	);
 
 	// Go through each group...