bug#56420: Link to Info manual from describe-package help

[Visuwesh]

[திங்கள் ஜூலை 11, 2022] Lars Ingebrigtsen wrote:

> But this reminds me -- why are we so strict about the Info links,
> anyway?  Could `(foo) Bar' in a doc string be anything but a manual
> reference?

Perhaps, the same could be said for man pages as well.
`man-page(section)' is probably refers to a manpage.  If we want to
avoid a lot of false positives, then we can restrict section to be
numeric I think?