Undeprecate Plugin::routes()

We'll leave it alone for now as it makes an easy to use API for simple
plugin setups.

src/Core/Plugin.php

@@ -324,12 +324,14 @@ class Plugin
     }
 
     /**
-     * Loads the routes file for a plugin, or all plugins configured to load their respective routes file
+     * Loads the routes file for a plugin, or all plugins configured to load their respective routes file.
      *
-     * @param string|null $plugin name of the plugin, if null will operate on all plugins having enabled the
-     * loading of routes files
+     * If you need fine grained control over how routes are loaded for plugins, you
+     * can use {@see Cake\Routing\RouteBuilder::loadPlugin()}
+     *
+     * @param string|null $plugin name of the plugin, if null will operate on all
+     *   plugins having enabled the loading of routes files.
      * @return bool
-     * @deprecated 3.5.0 Use Cake\Routing\RouteBuilder::loadPlugin() instead.
      */
     public static function routes($plugin = null)
     {