[Rd] documentation of intersect() on string vector and num vector and on duplicated elements (PR#14107)

[pengyu.ut at gmail.com]

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Version: 2.10.0
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Submission from: (NULL) (128.249.106.234)


The document on intersect()'s argument are spread into Arguments and Details
sections (see ?intersect). 

The following description is on the arguments (but from Details section). So I
think that it makes more sense to bring it to the Arguments section. May I
recommend such modification in future releases of R.

"Each of union, intersect, setdiff and setequal will discard any duplicated
values in the arguments, and they apply as.vector to their arguments (and so in
particular coerce factors to character vectors)."