Auto-build documentation

[wilzbach]

See also: https://gist.github.com/veelo/f7668510bad2e8c9212ab66104541fcc

It probably creating a bot account, s.t. there are no worries about sharing the GH_TOKEN with Travis.

Any volunteers? It shouldn't take more than half an hour to do so for the top five repos.

[wilzbach]

An experiment: dlang-community/libdparse#197

All repositories have the GH_TOKEN now set, so it should be as easy as modifying the .travis.yml in a similar way to dlang-community/libdparse#197

[wilzbach]

Example: http://libdparse.dlang.io/