Update WordPress Playground integration with Plugin Toggle and comprehensive documentation

playground/blueprint.json

@@ -1,4 +1,5 @@
 {
+  "$schema": "https://playground.wordpress.net/blueprint-schema.json",
   "landingPage": "/wp-admin/",
   "login": true,
   "steps": [
@@ -6,7 +7,7 @@
       "step": "installPlugin",
       "pluginData": {
         "resource": "wordpress.org/plugins",
-        "slug": "coblocks"
+        "slug": "plugin-toggle"
       }
     }
   ]