The About section should include a link to Documentation for Try F#

1. In particular, I'm looking for information about how Try F# persists changes.

From experiment, it appears to have persisted some of my changes, but not others.

2. Also, what is the purpose of the GitHub token input and how do I use it?

3. In case I accidentally delete stuff, maybe there could be a reset button to restore the original content.

4. Maybe the last link in the F# Basics section should be a blank page for experimentation (with just something like module Prototyping; open System; printfn "Hello, world!").