change main site title

@intrigeri suggested that the site name ("Tor Project Status") was
confusing because it might mean to imply the site would reflect the
status of the entire project, which it probably doesn't.

It certainly doesn't reflect the status of programmers' roadmaps, for
example, nor does it really accurately reflect the network health as a
whole. For both of those, there are better tools to look into this.

So let's rename that. @intrigeri suggested "tor infra status", I've
expanded it.