CONTRIBUTING.md file misses information about making commits

[sobolevn]

As I can see from your commits, you are using commitezen or similar tool to make commits.

And you also lint commits with commitlint afterwards.
But the docs misses that part.

So, it would be very nice for future contributors to add a note about it.

[manniL]

You are right, I'm using a specific commit message structure, though I don't use any tools for it.

I've added a short paragraph about conventional commits in the CONTRIBUTING.md :)

Thanks for the hint!