Add cleanup phpcr database

cookbook/cleanup-phpcr-database.rst

@@ -0,0 +1,14 @@
+Cleanup PHPCR database
+======================
+
+If you have an older installation of Sulu, you may be dealing with a database cluttered with outdated PHPCR properties.
+This is particularly common if you’ve made significant changes to your templates or content types over time.
+To tidy up your database, try running the following command:
+
+.. code-block:: bash
+
+    php bin/console sulu:document:phpcr-cleanup
+
+The command is quite powerful, but exercise caution when deploying it in a production environment. 
+It will remove all properties not currently utilized in your templates. To avoid potential pitfalls, ensure you have a 
+backup of your database in place before executing this command.

cookbook/index.rst

@@ -46,6 +46,7 @@ our recipes.
     user-context-caching
     build-admin-frontend
     multi-server-setup
+    cleanup-phpcr-database
 
 It is possible to work through the recipes, although most of the people will
 pick the ones, which are most similar to their own tasks. We're open to