Feature: option `--ignore` to skip certain directory/directories

Hi, I loved the app. Thank you so much 💜

I was wondering if we could have the option to skip certain directories. I am happy to try to come up with a draft PR if that's an interesting thing to have

The issue does not name files, tests, or an entry point. Start by locating the CLI argument parsing and directory traversal code, then determine how an ignore option should be represented and passed through; done means specified directories are skipped consistently.

Written by the indexing model from the issue text.