Organize readme

[john-cd]

The manual is quite complete, but is very "flat" and could use a bit more structure e.g.

• Features

  • Recipes
    • Regular recipes
    • Private recipes
    • Shebang recipes
      • Safer shebang recipes
    • Script recipes
    • ...
  • Aliases
  • Variables
  • Expressions
    • Conditional Expressions
    • ...
  • Attributes
  • Settings
  • Imports and Modules
    • ...

• Examples

  • Python
  • ...

Also consider adding to your book.toml - see https://rust-lang.github.io/mdBook/format/configuration/renderers.html

[output.html.fold]
enable = true # whether or not to enable section folding
level = 0 # the depth to start folding

[john-cd]

Also a lot of the stuff in https://github.com/casey/just/README.md could be moved to the manual, I think?

[casey]

Agreed, I think it could use better organization. I'm not sure about folding though, I like being able to ctrl-f find sections, which you wouldn't be able to do if they were folded.

The manual is generated from the readme, so the content is the same.