Add installation instructions to the README

README.md

@@ -5,3 +5,17 @@ This repository+branch contains Hazelcast tweaks (patches) for the original repo
 https://github.com/jenkinsci/ghprb-plugin
 
 See also https://plugins.jenkins.io/ghprb/
+
+## Installing
+
+Find the latest version in https://repo1.maven.org/maven2/com/hazelcast/jenkins/plugins/ghprb/
+
+Go to the Advanced settings tab in the Plugin Manager Jenkins configuration and
+fill the `hpi` URL to deploy.
+
+E.g. go to https://jenkins.hazelcast.com/manage/pluginManager/advanced
+and in the `Deploy Plugin` section fill:
+
+```
+https://repo1.maven.org/maven2/com/hazelcast/jenkins/plugins/ghprb/5.0.0/ghprb-5.0.0.hpi
+```