add dashboard data

Signed-off-by: Daniel González Lopes <danielgonzalezlopes@gmail.com>

README.md

@@ -2,7 +2,7 @@
 Github Traffic collects your repository's traffic data and exposes it as Prometheus metrics.
 
 ![Grafana dashboard](grafana_dashboard.png)
-*Grafana dashboard that displays the metrics generated by Github Traffic*
+*Grafana dashboard that displays the metrics generated by Github Traffic.*
 
 ## Quickstart
 
@@ -28,4 +28,7 @@ $ docker run --env-file .env -it -p 8001:8001 loadimpact/github-traffic
 ...
 Go to http://localhost:8001/metrics
 ```
-Profit!
+Profit!
+
+Now you can collect those metrics as you would do with any other service. To visualize them, we provide an example/template Grafana dashboard: https://grafana.com/grafana/dashboards/15000
+