update Helm documentation

Author: github-actions[bot]

charts/ecowitt-exporter/README.md

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 # ecowitt-exporter
 
-![Version: 2.1.1](https://img.shields.io/badge/Version-2.1.1-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square) ![AppVersion: 2.1.1](https://img.shields.io/badge/AppVersion-2.1.1-informational?style=flat-square)
+![Version: 2.1.2](https://img.shields.io/badge/Version-2.1.2-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square) ![AppVersion: 2.1.2](https://img.shields.io/badge/AppVersion-2.1.2-informational?style=flat-square)
 
 A Prometheus exporter for Ecowitt weather stations