Update Readme.md

closes https://github.com/assimp/assimp/issues/2248: Add lgtm badge.

Readme.md

@@ -1,7 +1,7 @@
 Open Asset Import Library (assimp)
 ==================================
 A library to import and export various 3d-model-formats including scene-post-processing to generate missing render data.
-### Current build status ###
+### Current project status ###
 [![Linux Build Status](https://travis-ci.org/assimp/assimp.svg)](https://travis-ci.org/assimp/assimp)
 [![Windows Build Status](https://ci.appveyor.com/api/projects/status/tmo433wax6u6cjp4?svg=true)](https://ci.appveyor.com/project/kimkulling/assimp)
 <a href="https://scan.coverity.com/projects/5607">
@@ -12,6 +12,7 @@ A library to import and export various 3d-model-formats including scene-post-pro
 [![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")
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/5be56faac64f46fc941ac890fb4febef)](https://www.codacy.com/app/kimkulling/assimp?utm_source=github.com&amp;utm_medium=referral&amp;utm_content=assimp/assimp&amp;utm_campaign=Badge_Grade)
+[![Total alerts](https://img.shields.io/lgtm/alerts/g/assimp/assimp.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/assimp/assimp/alerts/)
 <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.