Document how to check multiple requirements with pre-commit hooks

[atugushev]

Thanks for the issue! You should use a separate hook for each input requirement file, for example:

repos:
-   repo: https://github.com/jazzband/pip-tools
    rev: 5.3.1
    hooks:
      - id: pip-compile
        name: pip-compile setup.py
        files: ^setup\.py$
      - id: pip-compile
        name: pip-compile requirements-dev.in
        args: [requirements-dev.in]
        files: ^requirements-dev\.(in|txt)$
      - id: pip-compile
        name: pip-compile requirements-lint.in
        args: [requirements-lint.in]
        files: ^requirements-lint\.(in|txt)$

Would it be possible to add this somewhere in the documentation? I wasn't familiar at all with how pre-commit really worked so it took some digging until I realized that even if the pattern matches for files we would still need to feed the names in individually for each requirements file for it to work as intended.

Originally posted by @seanytak in #1208 (comment)

[microcat49]

Hey @atugushev,

Do you mind if I take this one?

[atugushev]

Hello @microcat49,

Please, feel free to 👍🏻

[microcat49]

Pull request #1387