Quick start guide

Document the process of adding and indexing the first repository, including a GUI walkthrough:

• Describe the different panes
• Explain IDs, BHash, etc
• Document most important features

Partially documented now: https://github.com/swampapp/swamp/blob/master/docs/quickstart.md

Investigate using https://github.com/mkdocs/mkdocs or Hugo to publish a docs site.