Add helm-hashtag plugin

https://github.com/balboah/helm-hashtag

docs/related.md

@@ -41,6 +41,7 @@ or [pull request](https://github.com/kubernetes/helm/pulls).
 - [helm-github](https://github.com/sagansystems/helm-github) - Plugin to install Helm Charts from Github repositories
 - [helm-monitor](https://github.com/ContainerSolutions/helm-monitor) - Plugin to monitor a release and rollback based on Prometheus/ElasticSearch query
 - [helm-k8comp](https://github.com/cststack/k8comp) - Plugin to create Helm Charts from hiera using k8comp
+- [helm-hashtag](https://github.com/balboah/helm-hashtag) - Plugin for tracking docker tag hash digests as values
 
 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.