DOC: Add Zenodo badge to README

Author: effigies

README.md

@@ -2,6 +2,7 @@
 [![Build Status (Linux and OS X)](https://travis-ci.org/bids-standard/pybids.svg?branch=master)](https://travis-ci.org/bids-standard/pybids)
 [![Build Status (Windows)](https://ci.appveyor.com/api/projects/status/5aa4c6e3m15ew4v7?svg=true)](https://ci.appveyor.com/project/chrisfilo/pybids-ilb80)
 [![Binder](https://mybinder.org/badge.svg)](https://mybinder.org/v2/gh/bids-standard/pybids/master)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.2537312.svg)](https://doi.org/10.5281/zenodo.2537312)
 
 PyBIDS is a Python library to centralize interactions with datasets conforming
 BIDS (Brain Imaging Data Structure) format.  For more information about BIDS