docs: remove broken badge and fix docker-compose snippet (#1025)

* Remove microbadger badge as it is shutdown
  source: https://twitter.com/microscaling/status/1361054926399557644
  source: https://web.archive.org/web/20210409135814/https://microbadger.com/shutdown
* Remove trailing space that breaks yaml formatting
* Adjust indentation for docker-compose snippet

README.md

@@ -9,7 +9,6 @@
   [![Circle CI](https://circleci.com/gh/containrrr/watchtower.svg?style=shield)](https://circleci.com/gh/containrrr/watchtower)
   [![codecov](https://codecov.io/gh/containrrr/watchtower/branch/main/graph/badge.svg)](https://codecov.io/gh/containrrr/watchtower)
   [![GoDoc](https://godoc.org/github.com/containrrr/watchtower?status.svg)](https://godoc.org/github.com/containrrr/watchtower)
-  [![Microbadger](https://images.microbadger.com/badges/image/containrrr/watchtower.svg)](https://microbadger.com/images/containrrr/watchtower)
   [![Go Report Card](https://goreportcard.com/badge/github.com/containrrr/watchtower)](https://goreportcard.com/report/github.com/containrrr/watchtower)
   [![latest version](https://img.shields.io/github/tag/containrrr/watchtower.svg)](https://github.com/containrrr/watchtower/releases)
   [![Apache-2.0 License](https://img.shields.io/github/license/containrrr/watchtower.svg)](https://www.apache.org/licenses/LICENSE-2.0)

docs/index.md

@@ -17,9 +17,6 @@
   <a href="https://godoc.org/github.com/containrrr/watchtower">
     <img alt="GoDoc" src="https://godoc.org/github.com/containrrr/watchtower?status.svg" />
   </a>
-  <a href="https://microbadger.com/images/containrrr/watchtower">
-    <img alt="Microbadger" src="https://images.microbadger.com/badges/image/containrrr/watchtower.svg" />
-  </a>
   <a href="https://goreportcard.com/report/github.com/containrrr/watchtower">
     <img alt="Go Report Card" src="https://goreportcard.com/badge/github.com/containrrr/watchtower" />
   </a>