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GH-35709: [R][Documentation] Document passing data to duckdb for windowed aggregates (#35882)

### Rationale for this change

#35702 documents how to use joins for computing windowed aggregates. This documents an alternative solution by passing data to duckdb. This use case was also mentioned on the [duckdb blog](https://duckdb.org/2021/12/03/duck-arrow.html).

### What changes are included in this PR?

Changes to vignette. 

* Closes: #35709

Authored-by: David Greiss <david.dgreiss@gmail.com>
Signed-off-by: Nic Crane <thisisnic@gmail.com>