docs: Add details

README.md

@@ -1,2 +1,8 @@
 # jenkins-extended
-Jenkins with certain plugins installed
+Jenkins with certain plugins installed.
+
+Helm: https://artifacthub.io/packages/helm/jenkinsci/jenkins/4.8.2
+
+## Why use a custom Jenkins image?
+Because of this:
+> This chart allows the user to specify plugins which should be installed. However, for production use cases one should consider to build a custom Jenkins image which has all required plugins pre-installed. This way you can be sure which plugins Jenkins is using when starting up and you avoid trouble in case of connectivity issues to the Jenkins update site.