Add Documentation for the CLI

[PranavVerma-droid]

Hi!
I noticed that yubal has a CLI, in the Code.
If might be helpful to add documentation for that CLI, plus refine it a little bit for it to be a self sustainable tool. People who want to do really complex stuff can just use to CLI to automate stuff. Adding Documentation for it can be really helpful.

[guillevc]

Hey, thanks for the suggestion! The CLI is maintained alongside the web UI, though I'm prioritizing the latter since it's what most people will use. Originally yubal started as a CLI tool, so documenting it makes sense—I'll add a section to the README so it's easier to discover.