Rust Documentation Writing Guidebook

[frewsxcv]

We've mentioned a couple times that it'd be great if we had a guide for writing Rust documentation, so let's start gathering resources/ideas

[frewsxcv]

https://github.com/jenniferlynparsons/awesome-writing

[Havvy]

Having an actual style guide that we can have consistent between the entire bookshelf would be nice.