Which directory to use for packagename-doc documentation files?

[Peter S Galbraith <GalbraithP@dfo-mpo.gc.ca>]

In the case where source package `foo' generates packages `foo'
and `foo-doc', it seems that concensus may be to put the
documentation files under /usr/share/doc/foo rather than
/usr/share/doc/foo-doc (except for a copy of foo-doc package
copyright and changelog files).

Examples:

 apache-doc -> /usr/share/doc/apache/
 cvs-doc -> /usr/share/doc/cvs/
 python-doc -> /usr/share/doc/python/

Counter-Examples:

 samba-doc -> /usr/share/doc/samba-doc/
 libtool-doc -> /usr/share/doc/libtool-doc/

Is that correct?
Should we use directory /usr/share/doc/foo ?

(I understand that a source package `foo-doc' that documents many
`foo-related' source pacakges may still be better off in
directory /usr/share/doc/foo-doc).

I'm just trying to convince myself to move some docs over in my
next upload of a source package that generates a -doc package.  I
think it would make the documentation easier to find (and
provides a shorter URL path!)

Thanks,
Peter