Added LGTM badges.

Author: Chessray

README.md

@@ -4,3 +4,5 @@ Helpful additions to MapStruct when using the Spring Framework.
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 [![Build Status](https://img.shields.io/travis/Chessray/mapstruct-spring-additions.svg)](https://travis-ci.org/Chessray/mapstruct-spring-additions)
 [![Coverage Status](https://img.shields.io/codecov/c/github/Chessray/mapstruct-spring-additions.svg)](https://codecov.io/gh/Chessray/mapstruct-spring-additions)
+[![Code Quality: Java](https://img.shields.io/lgtm/grade/java/g/Chessray/mapstruct-spring-additions.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/Chessray/mapstruct-spring-additions/context:java)
+[![Total Alerts](https://img.shields.io/lgtm/alerts/g/Chessray/mapstruct-spring-additions.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/Chessray/mapstruct-spring-additions/alerts)