Adds LGTM badges

README.md

@@ -3,6 +3,8 @@ HdrHistogram
 [![Gitter](https://img.shields.io/gitter/room/gitterHQ/gitter.svg)](https://gitter.im/HdrHistogram/HdrHistogram?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Build Status](https://travis-ci.org/HdrHistogram/HdrHistogram.svg?branch=master)](https://travis-ci.org/HdrHistogram/HdrHistogram) 
 [![Javadocs](http://www.javadoc.io/badge/org.hdrhistogram/HdrHistogram.svg)](http://www.javadoc.io/doc/org.hdrhistogram/HdrHistogram)
+[![Total alerts](https://img.shields.io/lgtm/alerts/g/HdrHistogram/HdrHistogram.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/HdrHistogram/HdrHistogram/alerts/)
+[![Language grade: Java](https://img.shields.io/lgtm/grade/java/g/HdrHistogram/HdrHistogram.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/HdrHistogram/HdrHistogram/context:java)
 
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 HdrHistogram: A High Dynamic Range (HDR) Histogram