improve prometheus docs

cmd/prometheus/Readme.md

 Run Grafana and Prometheus: `docker-compose up prometheus grafana`
 
+Go to: [localhost:3000](localhost:3000), admin/admin
+
 List of hosts and ports to collecting metrics is in: `./cmd/prometheus/prometheus.yml`
 
 Env variables:
@@ -7,9 +9,7 @@ Env variables:
 - `TG_PROMETHEUS_CONFIG` path to custom `prometheus.yml` file. Default is: `./cmd/prometheus/prometheus.yml`
 - `TG_GRAFANA_CONFIG` path to custom `grafana.ini file`. Default is: `./cmd/prometheus/grafana.ini`
 
-To add custom tg host: copy `./cmd/prometheus/prometheus.yml`, modify, pass new location by:
+To add custom TG host: copy `./cmd/prometheus/prometheus.yml`, modify, pass new location by:
 `TG_PROMETHEUS_CONFIG=/new/location/prometheus.yml docker-compose up prometheus grafana`
 
 
-Grafana: [localhost:3000](localhost:3000), admin/admin
-