Fix typo in AM client docs

content/docs/alerting/clients.md

@@ -28,7 +28,7 @@ the following format:
       "<labelname>": "<labelvalue>",
     },
     "startsAt": "<rfc3339>",
-    "endAt": "<rfc3339>"
+    "endsAt": "<rfc3339>"
     "generatorURL": "<generator_url>"
   },
   ...
@@ -48,4 +48,4 @@ The `generatorURL` field is a unique back-link which identifies the causing
 entity of this alert in the client. 
 
 Alertmanager also supports a legacy endpoint on `/api/alerts` which is
-compatible with Prometheus versions 0.16.2 and lower.
\ No newline at end of file
+compatible with Prometheus versions 0.16.2 and lower.