add rtd badge and link

README.md

@@ -3,7 +3,8 @@ Grove
 A collection of quantum algorithms built using Forest. Grove is licensed under the [Apache 2.0 
 license](https://github.com/rigetticomputing/grove/blob/master/LICENSE).
 
-[![Build Status](https://semaphoreci.com/api/v1/projects/af487aa0-bd6d-4b43-9610-9c8f3c3d787d/1123354/badge.svg)](https://semaphoreci.com/rigetti/grove)
+[![Build Status](https://semaphoreci.com/api/v1/projects/af487aa0-bd6d-4b43-9610-9c8f3c3d787d/1123354/badge.svg)](https://semaphoreci.com/rigetti/grove) 
+[![Documentation Status](https://readthedocs.org/projects/grove-docs/badge/?version=latest)](http://grove-docs.readthedocs.io/en/latest/?badge=latest)
 
 Grove currently includes algorithms for:
 
@@ -13,6 +14,11 @@ Grove currently includes algorithms for:
 * Phase Estimation
 * Quantum Teleportation
 
+Documentation
+-------------
+
+Documentation is hosted at http://grove-docs.readthedocs.io/en/latest/
+
 Installation
 ------------