Added CircleCI badge and info to README

README.md

@@ -1,3 +1,5 @@
+[![CircleCI](https://circleci.com/gh/edvald/garden/tree/master.svg?style=svg&circle-token=ac1ec9984d093f91e594e5a0a03b34cec2c2a093)](https://circleci.com/gh/edvald/garden/tree/master)
+
 # garden
 
 Just getting started now...
@@ -6,3 +8,12 @@ Just getting started now...
 
     npm test
 
+#### CI
+
+We use [Circle CI](https://circleci.com) for integration testing. Sometimes
+it can be useful to test and debug the CI build locally, particularly when 
+updating or adding dependencies. You can use their 
+[CLI](https://circleci.com/docs/2.0/local-jobs/) for that, which
+is installed automatically by the `./bin/bootstrap-osx` script. Once you
+have it installed you can run `circleci build` in the repo root to test 
+the build locally.