[ci skip] update README

README.md

@@ -1,3 +1,5 @@
+<img alt="salmon logo" src="https://github.com/COMBINE-lab/salmon/raw/master/doc/salmon_logo.png" width="600">
+
 [![Build Status](https://travis-ci.org/COMBINE-lab/salmon.svg?branch=master)](https://travis-ci.org/COMBINE-lab/salmon)
 [![Documentation Status](https://readthedocs.org/projects/salmon/badge/?version=latest)](http://salmon.readthedocs.org/en/latest)
 [![install with bioconda](https://img.shields.io/badge/install%20with-bioconda-brightgreen.svg?style=flat-square)](http://bioconda.github.io/recipes/salmon/README.html)
@@ -49,4 +51,4 @@ Chat live about Salmon
 
 You can chat with the Salmon developers and other users via Gitter!
 
-[![Join the chat at https://gitter.im/COMBINE-lab/salmon](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/COMBINE-lab/salmon?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join the chat at https://gitter.im/COMBINE-lab/salmon](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/COMBINE-lab/salmon?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)