Every flag parse_args in src/lib.rs accepts (--shout, --times, -L and so on) should be listed in the README's options table. Nothing checks that today, so a new flag can land undocumented.
Add a step to .g1t/workflows/ci.yml, before the tests, named Every flag is documented. It should find each flag the parser matches on and fail, naming the flags, when one of them does not appear in README.md. Keep it a short shell step; no new dependencies.