[Rd] Links to non-vignette documentation

[hadley wickham]

> They are meant to replace the INDEX, which you shouldn't need to create
> any more.  The DESCRIPTION file is still needed, but it contains more
> structured information meant for mechanical reading and processing; the
> package man page is meant to be the place to put things intended for
> people to read.

Do I need to keep the list of functions on the package man page in
sync myself, or will they be automatically rebuilt?  Is the intention
to eventually change help(package=XXX) to point to the package man
page?

Hadley