readme cloud sdk

Author: glytch

README.md

@@ -61,6 +61,8 @@ You can call `.publish` or instantiate an instance and call `#publish` for each
 
 ## Development
 
+You must install [Google Cloud SDK](https://cloud.google.com/sdk/). The specs in this project expect to be able to start a google cloud pubsub emulator locally.
+
 After checking out the repo, run `bundle` to install dependencies. Then, run `bundle exec rspec` to run the tests. You can also run `bundle exec bin/console` for an interactive prompt that will allow you to experiment.
 
 To release a new version: