Document that can be edited without vandalizing the README (warning: may not be safe for work)

[dwwoelfel]

Adding a new document here that people can test out refreshing on. The vandalism on the README was getting a bit annoying.

The markdown looks like:

[![cool demo doc](https://precursorapp.com/document/17592197510242.svg)](https://precursorapp.com/document/17592197510242)