Update related.md with new helm plugin

Add helm-github plugin to list in documentation

docs/related.md

@@ -37,6 +37,7 @@ or [pull request](https://github.com/kubernetes/helm/pulls).
 - [helm-secrets](https://github.com/futuresimple/helm-secrets) - Plugin to manage and store secrets safely
 - [helm-edit](https://github.com/mstrzele/helm-edit) - Plugin for editing release's values
 - [helm-gcs](https://github.com/nouney/helm-gcs) - Plugin to manage repositories on Google Cloud Storage
+- [helm-github](https://github.com/sagansystems/helm-github) - Plugin to install Helm Charts from Github repositories
 
 We also encourage GitHub authors to use the [helm-plugin](https://github.com/search?q=topic%3Ahelm-plugin&type=Repositories)
 tag on their plugin repositories.