targets missing package anchors in the "Rd cross-references" check.

[cpanse]

Specifically, please see the NOTEs about Rd file(s) with Rd \link{}
targets missing package anchors in the "Rd cross-references" check.

CRAN just changed its package web pages to providing (static) HTML
refmans in addition to PDF refmans, which needs Rd cross-references to
Rd \link{} targets not in the package itself nor in the base packages to
use package anchors, i.e., use \link[PKG]{FOO} (see section
"Cross-references" in "Writing R Extensions"): otherwise these links
will not work.