Specify prometheus server URL in README.md (#37)

README.md

@@ -240,7 +240,7 @@ docker run -d -p 3000:3000 --name=grafana grafana/grafana-enterprise
 ```
 
 You should be able to navigate to `http://localhost:3000` and login with `admin`/`admin`.
-You will need to add a datasource to Grafana. You can do this by navigating to `http://localhost:3000/datasources` and adding a Prometheus datasource. By default, the Prometheus server is running on `http://localhost:9090`. You can use this as the URL for the datasource.
+You will need to add a datasource to Grafana. You can do this by navigating to `http://localhost:3000/datasources` and adding a Prometheus datasource. By default, the Prometheus server is running on `http://localhost:9090`. You can use `http://prometheus:9090` as the server URL for the datasource.
 
 #### Useful Dashboards
 EigenDA provides a set of Grafana dashboards that provide insights into key performance indicators and health metrics of an EigenDA node. These dashboards can be accessed [here](monitoring/dashboards).