"texdoc --help" says:
The command `texdoc texdoc' gives you the full user guide in pdf.
Doing so, however, gives
texdoc info: texdoc aliased to texdoc/texdoc
Sorry, no documentation found for texdoc/texdoc.
The alias comes from /usr/share/texmf/texdoc/texdoc.cnf and is annotated with
the comment "avoid the man page to be displayed first".
It looks like neither the pdf documentation nor the man page for texdoc were
installed, and this despite me having texlive-documentation-{base,english}
installed.
I still haven't completely understood how the texlive packages on the gentoo
mirrors came to pass, but this archive here seems to contain the required
files:
http://ctan.org/get/systems/texlive/tlnet/2008/archive/bin-texdoc.doc.tar.lzma
Do you move them over to the Gentoo mirrors and include in a revbumped
texlive-core or texlive-documentation-* package?