[R] update docgen script to include arrow::one

[thisisnic]

Describe the enhancement requested

In #46619 (comment) we update docgen.R to remove references to arrow::one so that CI passes without complaining it's not a standalone function with an Rd file but we should either update the script so we can to refer to it without an Rd file, or generate the relevant Rd file

Component(s)

R

[amoeba]

I am just getting around to post-release stuff and was going to look at this. On the maint branch, I fixed this by just manually documenting it, see d03d3e7. I was thinking I might just cherry-pick that change into a minor PR on main but is there a better way?

[thisisnic]

I might just cherry-pick that change into a minor PR on main

@amoeba - sounds perfect and much simpler than messing around with the docgen script; thanks!

[amoeba]

PR up at #46648.

[amoeba]

Issue resolved by pull request 46648
#46648