Updated contributing guide

Author: ryanflorence

CONTRIBUTING.md

@@ -1,8 +1,38 @@
+## Pull Requests
+
+Please don't send pull requests for new features, open an issue to discuss.
+
+## Running tests
+
+This repo uses Jest.
+
+```sh
+yarn test
+# or
+yarn test --watch
+```
+
 ## Developing the examples
 
+First you have to link the lib.
+
 ```sh
+# from the root
+yarn build
 yarn link
-cd example
+```
+
+Then in one tab compile on file changes
+
+```
+yarn watch
+```
+
+And in another tab run the example
+
+```sh
+# in a new tab
+cd examples/<whatever>
 yarn link "@reach/router"
 yarn start
 ```