Rebuild manpages when they change on master

[robn]

After openzfs/zfs#17246 was merged, I was eagerly watching for zfs-rewrite.8.html to appear so I could point a couple of people at it. Alas, it has not.

I'm guessing that there's a manual button to press to update it? If so, can someone please hit it? And then, would it be possible to make it run when (say) anything under man/ changes, or, make it so other people can press the button? Can I help?

(showing that I'm alright at kernels, less good at webthings 😄)

Thanks :)