Merge pull request #2278 from assimp/kimkulling-dev

Update Readme.md

Readme.md

@@ -10,6 +10,7 @@ A library to import and export various 3d-model-formats including scene-post-pro
 </a>
 [![Coverage Status](https://coveralls.io/repos/github/assimp/assimp/badge.svg?branch=master)](https://coveralls.io/github/assimp/assimp?branch=master)
 [![Join the chat at https://gitter.im/assimp/assimp](https://badges.gitter.im/assimp/assimp.svg)](https://gitter.im/assimp/assimp?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Average time to resolve an issue](http://isitmaintained.com/badge/resolution/assimp/assimp.svg)](http://isitmaintained.com/project/assimp/assimp "Average time to resolve an issue")
 <br>
 
 APIs are provided for C and C++. There are various bindings to other languages (C#, Java, Python, Delphi, D). Assimp also runs on Android and iOS.