* Improve frontend development setup instructions
- Currently you recommend cloning the `home-assistant-polymer` repository directly. I assume you should instruct people to fork it, like you do in the [development environment documentation](https://developers.home-assistant.io/docs/en/development_environment.html)
- I had some trouble setting `development_repo` in macOS, I believe a trailing slash was necessary in the path. Have updated to a realistic macOS example path
* Link to Getting Started instead of macOS install instructions
* Revert comment change
* Change link to Installation Guide
* Adjust link to point to dev setup docs