For a long time it wasn't, but it looks like GitHub are slowly rolling this out to people.
Given that Jenkins is pretty popular, you'd think that they'd be able to sort something out with GitHub to get bumped up the list for something along these lines.
There's always the Cloudfare option, but I've never felt that this was an ideal solution when HTTPS should be extremely straightforward for GitHub to set up on their pages.
Please don't do this. It gives the user the illusion that their connection is secure, but the connection between Cloudflare and the site is not secure. Arguably it's better to encrypt some of the route rather than none of it, but also giving people a false sense of security comes with its own drawbacks.
You should set it to "Full" instead. That will use TLS but won't verify the domain name in the certificate like it does in "Strict" mode so you can still use Github pages.
Huh, they're using Github pages. I thought if you set up a redirect - a C dns response - to whatever.github.io, that would soothe the ssl complaints in the browser.
Looking at the dns records, it looks like they didn't do this, and instead set up an A record.
