Document all config options

[marlonrichert]

^{Originally posted by @chrishoage in https://github.com/marlonrichert/zsh-snap/discussions/86#discussioncomment-1844474}

It would be nice if the possible configuration options were documented somewhere.

The way I am setting up zsh-snap is perhaps a little non-standard but I have it in a submodule with my dotfiles so that i can stow it to the correct spot.

By default zsh-snap appears to use the same directory that znap lives. However I wanted my repos to be in a different spot as to not clutter the git repository my dotfiles are in.

I had to dig though the install script referenced above to find zstyle ':znap:*' repos-dir.

Please consider adding all the possible configuration options (if there are more) to the readme!

[marlonrichert]

I should also rename install.zsh to setup.zsh and document that you can run it again to re-configure the options.

[marlonrichert]

Should be covered by 008433949adbc8ccdedbebec6812fb6a72e01c65.