Add documentation about the `password-cli` executable

[Vlix]

We now have a working CLI (AFAWK) that can be used by anyone.

Adding this executable to hackage is not necessary as anyone can just build it, given this repo. But no one will if they don't know it exists, so we should "announce" the existence of this CLI in the password library('s documentation).

Maybe also make it prominent in the README so that it's the first thing anyone reads after "this is a package/library for handling passwords".

• Tell users of the password package/library that there's a password-cli executable in this repo
  • password package's README
  • password introduction documentation (in every algo's module)
  • the GitHub repository's README in general
• Fix the password-cli documentation while we're at it
  • Don't use "..." but '...' when giving console examples (any hash with $ in them will fail because of variable interpolation, e.g. bcrypt hashes)
  • Also address the above point literally in the text, as this can be an annoying "gotcha"

[cdepillabout]

executable to hackage is not necessary as anyone can just build it, given this repo

I'd recommend releasing it to Hackage, since Hackage is supposed to be for both end-user executables as well as libraries.

There are a few Linux distros that are able to automatically package things from Hackage, but won't (automatically) package Haskell executables that aren't uploaded to Hackage. A big benefit of uploading executables to Hackage is to make them automatically available to the users of these Linux distros.

I also agree with documenting the password-cli in the places you suggest.

[blackheaven]

Handled in #86