CLI: tidy

[casperdcl]

• tidy --help to match argparse style (follow-up to feature: add argument parsing and setup.py file for cli tool capability #46 <- fixes Basic CLI help text #43)
• add --print-completion using shtab

/CC @gagb

[casperdcl]

@microsoft-github-policy-service agree

[afourney]

Looks interesting. Can you say more about shtab?
What shell are you using that isn't already doing tab completion?

[casperdcl]

Ah @afourney your question(s) imply a fundamental misunderstanding. Clearly some docs are missing here. Unsure about how much detail you'd prefer to see in the GitHub flavoured markdown README, though.

For example/comparison, DVC details its end-user completion usage in separate per-OS/shell tabs at https://dvc.org/doc/install/completion

[gagb]

With this PR:

main:

@casperdcl thank you for the PR. This is what I see. I am not sure if the --print-completion is helpful?
I am open to simplifying the help instructions but not sure if adding another dependency is a good idea -- the syntax is already simple and helps keep the package lightweight? cc @afourney @jackgerrits

[casperdcl]

ok rebased & removed shtab now