hhvm man page generates incorrectly due to ronn parser bug

Because of https://github.com/rtomayko/ronn/pull/65

It creates the file incorrectly
https://github.com/facebook/hhvm/blob/master/hphp/doc/man/hhvm.1#L110

such that line 110 looks like a macro to man.

I could submit a PR to fix it myself, but @Jo-Con-El wants to try to fix the ronn source,
which is not actually included in the HHVM repository (likely due to ruby dependency).

Just posting a ticket, so it it doesn't get lost in the shuffle.

NOTE: ronn seems unmaintained, maybe there is something nice in python
that can handle this task instead.