Add pre-commit hooks configuration

[skycaptain]

This adds support for using this repo as pre-commit hook (https://pre-commit.com/). To add editorconfig-checker to your repository add this to your .pre-commit-config.yaml:

repos:
-   repo: https://github.com/editorconfig-checker/editorconfig-checker.python
    rev: ''  # pick a git hash / tag to point to
    hooks:
    -   id: editorconfig-checker

pre-commit also supports building go packages directly from repository, however this would require go on the client. Since pre-commit is also written in Python, and thus no further dependency is produced, this wrapper is preferred instead. See editorconfig-checker/editorconfig-checker#133 for details.

The use of types: [text] is debatable. If I understood the documentation correctly, it filters files which are recognized by Git as text files before passing to editorconfig-checker. This is merely an optimization and can be overwritten by the user if necessary. However, if Git recognizes a file with the wrong type at might be silently ignored. @mstruebing opinions? Is this even necessary or would our just pass all files to editorconfig-checker?

[mstruebing]

Is this even necessary or would our just pass all files to editorconfig-checker?

editorconfig-checker tries to filter out non-text files too, so it would be filtered anyway if you would pass it to editorconfig-checker.
I might think that pre-commit does a slightly better job in filtering so I would let pre-commit do the filtering.

[mstruebing]

@mmicu any opinions or blocker about this?

[mstruebing]

ping @mmicu

[mmicu]

Hi. I think that it could be an useful tool to use. I'm going to review and merge the commit. Thanks for your pull request.

[skycaptain]

Thanks @mmicu. Would it make sense to also commit the README.md change to the parent project's README?

[skycaptain]

You would also need to release (or atleast tag) a new version to make this change work.

[mstruebing]

I think it would make sense, also it would make sene to mention here: https://github.com/editorconfig-checker/editorconfig-checker.github.io

Feel free to add documentation :)