[llvm-dev] [docs] Updating the sphinx build bots

[Dmitri Gribenko via llvm-dev]

Hi,

Thanks for bringing this up. I am reluctant to update to recommonmark
>= 0.4.0, because it is not available in any Ubuntu version, Debian
Testing or even Debian Unstable.

While we could do something custom on the buildbot, I think it would
be a disservice for our users to use a library that is not packaged in
modern operating systems yet.

Dmitri