Add install instructions

Author: Tortoaster

README.md

@@ -2,6 +2,13 @@
 
 Helm chart for deploying a pokertool.
 
+## Install
+
+```shell
+helm repo add pokertool-repo https://alliander-opensource.github.io/pokertool-chart
+helm install my-pokertool pokertool-repo/pokertool --set ingress.domain=mypokertool.com
+```
+
 ## Relevant repositories
 
 - [Frontend](https://github.com/alliander-opensource/pokertool-frontend)