Fix grafana support metadata
diff --git a/nginx/meta/grafana.yml b/nginx/meta/grafana.yml
index 60b5b4a..a03677a 100644
--- a/nginx/meta/grafana.yml
+++ b/nginx/meta/grafana.yml
@@ -1,3 +1,4 @@
 dashboard:
   nginx:
+    format: json
     template: nginx/files/grafana_influxdb.json