chore(docs.angularjs.org): add csp headers for csp example

Fixes angular#16270

Author: Narretz

scripts/docs.angularjs.org-firebase/firebase.json

@@ -15,6 +15,13 @@
       }
     ],
     "headers": [
+      {
+        "source": "/examples/**.csp/*.html",
+        "headers": [{
+          "key": "Content-Security-Policy",
+          "value": "default-src 'self'"
+        }]
+      },
       {
         "source": "/Error404.html",
         "headers" : [{