Adds zenodo configuration (#74)

* adds zenodo configuration
* added how to cite section

Author: balopat

.zenodo.json

@@ -0,0 +1,13 @@
+{
+    "description": "This project contains modules for running quantum computing applications and experiments through Cirq and Google's Quantum Computing Service.",
+    "license": "Apache-2.0",
+    "title": "ReCirq",
+    "upload_type": "software",
+    "creators": [
+        {
+            "affiliation": "Google Inc",
+            "name": "Quantum AI team and collaborators"
+        }
+    ],
+    "access_right": "open"
+}

README.md

@@ -32,3 +32,21 @@ chemistry and materials science, please see
 
 
 ReCirq is not an official Google product. Copyright 2020 Google.
+
+# How to cite ReCirq
+
+ReCirq is uploaded to Zenodo automatically. Click on this badge [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.3992331.svg)](https://doi.org/10.5281/zenodo.3992331) to see all the citation formats for all versions.
+
+An equivalent BibTex format reference is below for all the versions:
+
+```
+@software{quantum_ai_team_and_collaborators_2020_3992331,
+  author       = {Quantum AI team and collaborators},
+  title        = {ReCirq},
+  month        = Aug,
+  year         = 2020,
+  publisher    = {Zenodo},
+  doi          = {10.5281/zenodo.3992331},
+  url          = {https://doi.org/10.5281/zenodo.3992331}
+}
+```