[$] Pulling GitHub into the kernel process

There is an ongoing effort to "modernize" the kernel-development process;so far, the focus has been on providing bettertools that can streamline the usual email-based workflow. But that"email-based" part has proven to be problematic for some potentialcontributors, especially those who might want to simply submit a small bugfix and are not interested in getting set up with that workflow. Theproject-hosting "forge" sites, like GitHub and GitLab, provide a nearlyfrictionless path for these kinds of one-off contributions, but they donot mesh well-at all, really-with most of mainline kernel development.There is some ongoing work that may change all of that, however.