Doc: Coding Style

[chillenzer]

Hi, just noticed that the Commit rules page talks about coding style guidelines but actually links to the contributing repo and not the Coding Guidelines page of the docs. Also, the latter seems to be outdated (at the very least concerning the clang-format version requirements). We should clean this up.

[psychocoderHPC]

We should change the link and add a sentence that code style changes will be voted in the separate repository.