Fix typo in sample response JSON in API docs (#4345)

Author: rrashidov

docs/v3/source/includes/api_resources/_deployments.erb

@@ -109,7 +109,7 @@
       },
       "strategy": "rolling",
       "options" : {
-        "max_in_flight": 1,
+        "max_in_flight": 1
       },
       "droplet": {
         "guid": "44ccfa61-dbcf-4a0d-82fe-f668e9d2a962"