arrow

MINOR: [R] Fix URL in R package release checklist (#33927)

There was an incorrect URL in R package release checklist which was [flagged in a previous PR](https://github.com/apache/arrow/pull/14678/files#r1036249351), but the suggested change was never merged.


Lead-authored-by: Nic Crane <thisisnic@gmail.com>
Co-authored-by: Dewey Dunnington <dewey@dunnington.ca>
Signed-off-by: Jacob Wujciak-Jens <jacob@wujciak.de>