docs(mok): Update README

charts/mok/README.md

 # mok
 
-![Version: 0.3.0](https://img.shields.io/badge/Version-0.3.0-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square)
+![Version: 0.3.1](https://img.shields.io/badge/Version-0.3.1-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square)
 
 Mail on Kubernetes (MoK) is a project to deploy a functional mailserver that runs without a database server on Kubernetes, taking advantage of configmaps and secret.
 
@@ -55,7 +55,7 @@ Mail on Kubernetes (MoK) is a project to deploy a functional mailserver that run
 | postfix.affinity | object | `{}` |  |
 | postfix.image.pullPolicy | string | `"IfNotPresent"` |  |
 | postfix.image.repository | string | `"quay.io/shivering-isles/postfix"` | postfix container image |
-| postfix.image.tag | string | `"0.1.1"` | Overrides the image tag whose default is "latest" |
+| postfix.image.tag | string | `"0.2.1"` | Overrides the image tag whose default is "latest" |
 | postfix.imagePullSecrets | list | `[]` |  |
 | postfix.nodeSelector | object | `{}` |  |
 | postfix.podAnnotations | object | `{}` |  |