Update README.md (#179)

Add link to platform guide.

Author: Akshith Yellapragada

README.md

@@ -16,9 +16,13 @@ learn more on the [thoughtbot website].
 
 ## Deployment
 
+There are detailed install instructions in our [AWS Platform Guide].
+
 - [AWS](./aws/README.md)
 - [Other](./platform/README.md)
 
+[AWS Platform Guide]: https://thoughtbot.atlassian.net/wiki/spaces/APG/pages/11304961/Provision+Platform+Resources
+
 ## Development
 
 Please see [CONTRIBUTING.md](./CONTRIBUTING.md).