GCM for Chrome documentation

chrome/common/extensions/docs/templates/json/intro_tables.json

 {
   "alarms": {
     "Learn More": [
       {
         "link": "event_pages.html",
         "text": "Event Pages"
       }
     ]
   },
   "app_runtime": {
@@ skipping 99 matching lines @@
       {
         "link": "angular_framework.html",
         "text": "Build Apps with AngularJS"
       },
       {
         "link": "https://developers.google.com/live/shows/7320022-1001/",
         "text": "Chrome Apps Office Hours: TextDrive and AngularJS"
       }
     ]
   },
+  "gcm": {
+    "Learn More": [
+      {
+        "link": "cloudMessagingV2.html",
+        "text": "Google Cloud Messaging"
+      }
+    ]
+  },
   "identity": {
     "Learn More": [
       {
         "link": "app_identity.html",
         "text": "Identify User"
       }
     ]
   },
   "mediaGalleries": {
     "Permissions": [
@@ skipping 161 matching lines @@
     ]
   },
   "windows": {
     "Permissions": [
       {
         "partial": "intro_tables/windows_permissions.html"
       }
     ]
   }
 }