return better data for ping api, add to readme

tubearchivist/api/README.md

@@ -104,3 +104,16 @@ POST /api/download/
 
 ## Download Queue Item View
 /api/download/\<video_id>/
+
+
+## Ping View
+Validate your connection with the API  
+GET /api/ping
+
+When valid returns message with user id: 
+```json
+{
+    "response": "pong",
+    "user": 1
+}
+```

tubearchivist/api/views.py

@@ -271,7 +271,7 @@ class PingView(ApiBaseView):
     @staticmethod
     def get(request):
         """get pong"""
-        data = {"pong": request.user.id}
+        data = {"response": "pong", "user": request.user.id}
         return Response(data)