Incorrect path on How to Contribute page

[iansu]

In the "Development Workflow" section of the "How to Contribute" page the instructions for using yarn link refer to the wrong path. The instructions say to navigate to ~/path_to_your_react_clone/build/packages/react but there is no packages directory inside of build. I believe this should be node_modules instead.

Happy to submit a PR if this is actually an error.

[gaearon]

Please do, we indeed renamed it.