AFAICS, the only place where there are instructions for the pre-commit git hook is here:
eb4e348

It really should be in the main documentation somewhere, perhaps in CODING_STANDARD, or in a CONTRIBUTING.md file (https://github.com/blog/1184-contributing-guidelines), which could also reference CODING_STANDARD and anything else people should know before contributing (e.g. license agreement)