feat(helmfile): introduce helmfile plugin

plugins/helmfile/README.md

@@ -0,0 +1,16 @@
+# Helmfile plugin
+
+This plugin adds completion and aliases for [Helmfile](https://helmfile.readthedocs.io/), the declarative helm charts deployer.
+
+To use it, add `helmfile` to the plugins array in your zshrc file:
+
+```zsh
+plugins=(... helmfile)
+```
+
+## Aliases
+
+| Alias |  Full command          |
+| ----- | ---------------------- |
+| hf    | helmfile               |
+| hfi   | helmfile --interactive |