Add citation guidelines and DOI badge

Author: JPTIZ

README.md

@@ -2,7 +2,6 @@
 
 **TL;DR: Scientific code needs to be open source in order to be useful and peer reviewed.**
 
-
 ## Support The Manifesto
 Right now we're in the [60 day consultation period](roadmap.md) to allow potentially interested parties to comment on the manifesto draft before we officially begin to collect signatures.
 
@@ -12,23 +11,31 @@ If you'd like to comment on the draft during the consultation period, you can do
 
 - Fill out [this form](https://goo.gl/forms/dgvUjzkEYJqJJJrx2) with your feedback comments.
 - Create a [GitHub issue](https://github.com/codeisscience/manifesto/issues/new?title=[Manifesto%20Comment]) (requires GitHub account).
-- [Fork the repo](https://github.com/codeisscience/manifesto/fork) and create a pull request with suggested amendments. 
+- [Fork the repo](https://github.com/codeisscience/manifesto/fork) and create a pull request with suggested amendments.
 
 ## Mailing list
 
-[Sign up for updates on the Code is Science Manifesto](https://goo.gl/forms/gzd3dugLkZV92gms1). 
+[Sign up for updates on the Code is Science Manifesto](https://goo.gl/forms/gzd3dugLkZV92gms1).
 
 ## Badges
-After signing, you can add ![https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg](https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg) to all your Github projects and your profile. Remember to link back to the [Code is Science Manifesto](https://codeisscience.github.io/manifesto/) page. 
+After signing, you can add ![https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg](https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg) to all your Github projects and your profile. Remember to link back to the [Code is Science Manifesto](https://codeisscience.github.io/manifesto/) page.
 
 ```
 ![https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg](https://img.shields.io/badge/Code%20is%20Science%20Manifesto-%E2%9C%93-brightgreen.svg)
 ```
 
 ## Contributors
-We are in the process of requesting permission to publish a full list of contributors. 
+We are in the process of requesting permission to publish a full list of contributors.
 
 ### Stickers
-Stickers will be available soon. 
+Stickers will be available soon.
+
+## Citation
 
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.3484107.svg)](https://doi.org/10.5281/zenodo.3484107)
 
+Every release of this repository has a DOI related to it. You can either cite
+it directly or, more preferably, use the [CITATION.cff](./CITATION.cff) file
+along with [a tool](https://citation-file-format.github.io/#/tools) to properly
+use it (such as for [BibTeX generation from CFF
+file](https://github.com/citation-file-format/cff-converter-python)).