devel/qt5-qdoc: Update for generating HTML documentation out of sourcecode

The port now includes the global files needed to generate Qt-style
documentation for ports like qtcreator and qbs. Bump PORTREVISION
to reflect the update.

Pre-work for the Qt Creator 4.0 update.

PR: 209911
Submitted by: Ralf Nolden <nolden@kde.org> (kde)