ARROW-11729: [R] Add examples to datasets documentation
ARROW-11729: [R] Add examples to datasets documentation

Closes #9748 from pachadotdev/ARROW-11729

Lead-authored-by: Pachamaltese <75919093fc69d86e4175e8385616cffbbcd14f7f@dcc.uchile.cl>
Co-authored-by: Mauricio Vargas <bdf939fe899d4e93a5c58aaa48c95c68c6e4fc16@uc.cl>
Co-authored-by: Mauricio Vargas <75919093fc69d86e4175e8385616cffbbcd14f7f@dcc.uchile.cl>
Co-authored-by: Pachá <75919093fc69d86e4175e8385616cffbbcd14f7f@dcc.uchile.cl>
Co-authored-by: Jonathan Keane <28d17c45cab2bb8b25bea44a915713e26ce37e1b@gmail.com>
Signed-off-by: Jonathan Keane <28d17c45cab2bb8b25bea44a915713e26ce37e1b@gmail.com>

icexelloss/arrow,apache/arrow,kou/arrow,icexelloss/arrow,laurentgo/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,wesm/arrow,icexelloss/arrow,laurentgo/arrow,laurentgo/arrow,apache/arrow,laurentgo/arrow,kou/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,wesm/arrow,wesm/arrow,apache/arrow,apache/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,apache/arrow,laurentgo/arrow,wesm/arrow,laurentgo/arrow,kou/arrow,apache/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,kou/arrow,laurentgo/arrow,apache/arrow,kou/arrow,laurentgo/arrow,laurentgo/arrow,apache/arrow,laurentgo/arrow,kou/arrow,wesm/arrow,kou/arrow,wesm/arrow,wesm/arrow,apache/arrow,icexelloss/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,wesm/arrow,kou/arrow,wesm/arrow,kou/arrow,wesm/arrow,laurentgo/arrow,apache/arrow,kou/arrow,apache/arrow,laurentgo/arrow,icexelloss/arrow,kou/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,wesm/arrow,apache/arrow