GH-49000: [R] Warning building docs due to unresolved references to base R functions

[thisisnic]

Rationale for this change

Warning due to bad docs link

What changes are included in this PR?

Fix doc generation stuff to point to right place

Are these changes tested?

Test with make doc locally, worked.

Are there any user-facing changes?

Docs links work better?

• GitHub Issue: [R] Warning building docs due to unresolved references to base R functions #49000

[nealrichardson]

These warnings are from roxygen2::roxygenize() not CRAN? Among the things that are odd here are (1) the resulting man/acero.Rd is not changed, and (2) Arithmetic encompasses so many operators, not just %% and %/% (like + etc.), so why are those the only ones flagged? I wonder if this should be a bug report to roxygen2 then.

[thisisnic]

Hmm, looks like this is to do with r-lib/roxygen2#1612 but it'll be fixed in r-lib/roxygen2#1758 so I'm closing this PR