Add project status notice (#209)

* Add project status notice

* Add link to maintenance issue

Author: jmewes

README.md

@@ -1,5 +1,6 @@
 # Spring REST Docs API specification Integration
 
+[![oss lifecycle](https://img.shields.io/badge/oss_lifecycle-maintenance-yellow.svg)](https://github.com/ePages-de/restdocs-api-spec/issues/204)
 ![](https://img.shields.io/github/license/ePages-de/restdocs-openapi.svg)
 [![Build Status](https://travis-ci.com/ePages-de/restdocs-api-spec.svg?branch=master)](https://travis-ci.com/ePages-de/restdocs-api-spec)
 [![Maven Central](https://img.shields.io/maven-central/v/com.epages/restdocs-api-spec)](https://search.maven.org/artifact/com.epages/restdocs-api-spec)