Better Getting started

[isobar-bcarpenter]

Current one is crap, needs to cover the case of someone who doesn't have nodejs but has a clean SF install.

• [ ] Setting up node, yarn and it's dependencies
• [ ] Bootstraping with Yeoman
• [ ] Integrating with Sitefinity
• [ ] Basic Usage
• [ ] Explanation of build system
• [ ] Upgrading feather with Yeoman