docs: cli usage

[AriPerkkio]

• Adds documentation of the CLI flags to the README. Currently only some of the options are documented and most are just missing.
• Fixes duplicate id of anchor link <a id="optionsremove">.

I was looking for documentation for -t flag that was mentioned in some example setup. Since the README had some CLI arguments present but not the -t one, I thought -t does not exist. Had to look through source codes to see what it meant.

Thanks for awesome project, I've been using it for years! 🙌