add usage docs

README.md

@@ -14,6 +14,20 @@ git clone git@github.com:hastic/hastic-grafana-graph-panel.git
 and restart your `$GRAFANA_PATH/bin/grafana-server` server.
 
 
+# Usage
+
+You should have [hastic-server](https://github.com/hastic/hastic-server) running to use anomaly detection.
+
+- set [template variable](http://docs.grafana.org/reference/templating/) `$backendUrl` with URL of your hastic-server instance (e.g. `http://localhost:8000`) in your dashboard
+- set metrics in `Metrics` tab
+- go to `Analytics tab` and create new anomaly
+- label your data:
+  - click button with chart icon
+  - highlight anomalies on graph holding Ctrl button
+  - when you finished labeling - click button with chart icon once more
+- you should see `Learning` status while hastic-server is learning (first learning can take a while)
+- when `Learning` status dissapear - you should see anomalies labeled in your graph
+
 
 # Development