documentation sync issues with the source in trunk

We provide online access to the built versions of the documentation for our
major packages on the website (well, of ogg an vorbis anyway, the rest should do
as well) However, the files in e.g. xiph.org/ogg/vorbis/doc are separate from
those in trunk/vorbis/doc and it's difficult to remember to keep them in sync.

We need some automation here. For example, replacing the files with a separate
checkout+make, or adding an upload script to be run as part of the release process.