rtmp-services: Add YouTube Gaming reference

YouTube Gaming is live since today (26 August 2015) and people will ask
for it.
This makes it a bit clearer that YouTube and YouTube Gaming
(which share the same ingestion system) work with OBS MP.

plugins/rtmp-services/data/services.json

@@ -118,7 +118,7 @@
             }
         },
         {
-            "name": "YouTube",
+            "name": "YouTube / YouTube Gaming",
             "common": true,
             "servers": [
                 {