> Sorry, but the Wiki content is not really a documentation set.

Besides

> that, we still need PDFs and HTMLs, i.e. LangRef, ApiGuide, etc. And
> they're likely to be bound to FB versions. How do you suggest to

create

> them from the Wiki contents which is supposed to have a mixture of
> various information inside the every topic?
>

That's simple. A good engine (like wikka for instance -- I use it for
years) will be extensible in at least two aspects: "actions" and
"formatters". Actions are little scripts embedded in the markup, sorta
like {{image url="some-image"}}, while formatters are scripts that
embed markup, and transform it somehow, sorta like %%(very-special-
text)this text will be displayed differently, saved to a database or
whatever%%.

So it's just a matter of inventing your own "actions" and "formatters"
to give semantics to various paragraphs. It's like phpDocumentor tags,
if you like.