review clig.dev for CLI guidelines

take inspiration from https://clig.dev/ for best practices when it comes to CLI tools, like capa.

don't necessarily re-write things to adhere to the style, especially when we already have a working solution. however, if they have some good suggestions, see if we can incorporate them as appropriate.

i'll mark this as #help-wanted and #good-first-issue so that contributors can take suggestions from the items below and propose changes in dedicated PRs and issues. note: before spending a lot of time addressing one of these points, please coordinate with us to ensure we all agree on the design and/or wording.