`man cp` doesn’t document the `-R` option

The manpage for cp/ucp shows the --recursive and -r options for recursive copying, but does not mention -R. All of the following work exactly as expected after running rm -rf directory elsewhere && mkdir directory:

$ "$(brew --prefix uutils-coreutils)"/libexec/uubin/cp -r          directory elsewhere
$                                                  ucp -r          directory elsewhere


$                                                  ucp --recursive directory elsewhere
$ "$(brew --prefix uutils-coreutils)"/libexec/uubin/cp --recursive directory elsewhere


$ "$(brew --prefix uutils-coreutils)"/libexec/uubin/cp -R          directory elsewhere
$                                                  ucp -R          directory elsewhere

but the last two lines use -R, which is undocumented in the manpage, and is the only POSIX-guaranteed option for recursive copying.

Start at src/uu/cp/src/cp.rs around lines 475-485, where the documented cp options are defined, and inspect how that text feeds the cp/ucp manpage. Confirm the generated documentation includes -R alongside the recursive options, then run the relevant documentation or cp checks if available.