[Rd] Links to non-vignette documentation

[hadley wickham]

Section 1.4 of Writing R Extensions says:

In addition to the help files in Rd format, R packages allow the
inclusion of documents in arbitrary other formats. The standard
location for these is subdirectory inst/doc of a source package, the
contents will be copied to subdirectory doc when the package is
installed. Pointers from package help indices to the installed
documents are automatically created. Documents in inst/doc can be in
arbitrary format, however we strongly recommend to provide them in PDF
format, such that users on all platforms can easily read them.

Where are these pointers created?  I have a package with a pdf file
(introduction.pdf) in inst/doc but I can't find a link to it from the
documentation (eg. from help.start() or help(package=...)

Is there anyway to have my pdf documentation listed under vignettes
other than making it a sweave file?

Hadley