As usual, I'm tracking this outage over at StatusGator: https://statusgator.io. If you want alerts on this sort of thing, it can post to your Slack and the like.
The most interesting thing to me about GitHub outages is how many services it affects. I always get notifications for at least 20 or 30 services which all proactively and automatically post warnings about their GitHub integrations potentially being down. A lot of services integrate with GitHub!