Add citation info.

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://travis-ci.org/malmaud/TensorFlow.jl.svg?branch=master)](https://travis-ci.org/malmaud/TensorFlow.jl)
 [![codecov.io](http://codecov.io/github/malmaud/TensorFlow.jl/coverage.svg?branch=master)](http://codecov.io/github/malmaud/TensorFlow.jl?branch=master)
-[![DOI](https://zenodo.org/badge/46368063.svg)](https://zenodo.org/badge/latestdoi/46368063)
+[![DOI](http://joss.theoj.org/papers/10.21105/joss.01002/status.svg)](https://doi.org/10.21105/joss.01002)
 
 A wrapper around [TensorFlow](https://www.tensorflow.org/), a popular open source machine learning framework from Google.
 
@@ -139,6 +139,14 @@ julia> Pkg.build("TensorFlow")
 $ pip install --upgrade tensorflow
 ```
 
+## Citing
+
+If you use this software in your research, we would really appreciate if you cite us.
+
+```
+Malmaud, J. & White, L. (2018). TensorFlow.jl: An Idiomatic Julia Front End for TensorFlow. Journal of Open Source Software, 3(31), 1002, https://doi.org/10.21105/joss.01002
+```
+
 ## Optional: Using a custom TensorFlow binary
 
 To build TensorFlow from source, or if you already have a TensorFlow binary that you wish to use, follow [these instructions](https://malmaud.github.io/TensorFlow.jl/latest/build_from_source.html). This is recommended by Google for maximum performance, and is currently needed for Mac OS X GPU support.