docs: integrate payload guide (#13162)

* docs: integrate payload guide

* remove todo

* fix vale errors

* change items per row in integrations page

* updates to guide

www/apps/resources/generated/generated-how-to-tutorials-sidebar.mjs

@@ -487,6 +487,15 @@ const generatedgeneratedHowToTutorialsSidebarSidebar = {
           "description": "Learn how to generate invoices for orders in your Medusa store.",
           "children": []
         },
+        {
+          "loaded": true,
+          "isPathHref": true,
+          "type": "ref",
+          "title": "Integrate Payload CMS",
+          "path": "/integrations/guides/payload",
+          "description": "Learn how to integrate Payload CMS with Medusa to manage your product content.",
+          "children": []
+        },
         {
           "loaded": true,
           "isPathHref": true,