Nice! I didn't know about cog.

I've developed a simple "codeblocks" tool that to keep README.md up-to-date. In your example, here is how to insert the latest `--help` output:

    codeblocks usage-auth README.md -- google-drive-to-sqlite auth --help

Where "usage-auth" is the block language in README.md:

    Full `--help`:
    ```usage-auth
    Usage: ...
    ```

Checking is also possible:

    codeblocks --check usage-auth README.md -- google-drive-to-sqlite auth --help

It's not as generic as cog, but does not require writing codegen scripts inside Markdown file.

https://github.com/shamrin/codeblocks