update README

README.md

@@ -3,6 +3,7 @@
 [![Build Status](https://ci.bunix.de/api/badges/bunix42/docker-borgbackup-exporter/status.svg)](https://ci.bunix.de/bunix42/docker-borgbackup-exporter)
 [![hadolint](https://img.shields.io/badge/hadolint-passing-brightgreen)](https://github.com/hadolint/hadolint)
 [![pre-commit](https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit&logoColor=white)](https://github.com/pre-commit/pre-commit)
+[![docker](https://img.shields.io/docker/v/bunix42/docker-borgbackup-exporter)](https://registry.hub.docker.com/r/bunix42/docker-borgbackup-exporter)
 
 This is a simple cron based exporter for borg backup metrics, that are supposed to be delivered via any means like a simple nginx or using node_exporters textfile or adding pushgateway pushes.
 
@@ -32,4 +33,9 @@ services:
 
 volumes:
   exporter-data:
-```
+```
+
+## inspired by
+
+* https://github.com/mad-ady/prometheus-borg-exporter
+* https://github.com/teemow/prometheus-borg-exporter