[MINOR][R][DOCS] Fix misplaced brackets in SparkR:::mapValues doc
[MINOR][R][DOCS] Fix misplaced brackets in SparkR:::mapValues doc

### What changes were proposed in this pull request?

Fixes usage `example` for `SparkR:::mapValues`.

### Why are the changes needed?

At the moment. example has invalid syntax and yields warnings when running additional checks on SparkR codebase.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Manual testing.

Closes #34682 from zero323/pair-rdd-doc-fix.

Authored-by: zero323 <0f81822ec43dc7f424811d0a422871ea124aa3dd@gmail.com>
Signed-off-by: zero323 <0f81822ec43dc7f424811d0a422871ea124aa3dd@gmail.com>

hvanhovell/spark,shaneknapp/spark,HyukjinKwon/spark,shaneknapp/spark,rednaxelafx/apache-spark,apache/spark,holdenk/spark,witgo/spark,srowen/spark,JoshRosen/spark,zzcclp/spark,ueshin/apache-spark,hvanhovell/spark,zzcclp/spark,zzcclp/spark,zero323/spark,apache/spark,ueshin/apache-spark,WeichenXu123/spark,dongjoon-hyun/spark,wangyum/spark,cloud-fan/spark,dongjoon-hyun/spark,zero323/spark,srowen/spark,zero323/spark,shaneknapp/spark,srowen/spark,hvanhovell/spark,nchammas/spark,cloud-fan/spark,dongjoon-hyun/spark,zero323/spark,witgo/spark,ueshin/apache-spark,vinodkc/spark,srowen/spark,cloud-fan/spark,shaneknapp/spark,zzcclp/spark,mahak/spark,HyukjinKwon/spark,HyukjinKwon/spark,nchammas/spark,holdenk/spark,apache/spark,nchammas/spark,rednaxelafx/apache-spark,apache/spark,cloud-fan/spark,ueshin/apache-spark,wangyum/spark,xuanyuanking/spark,gengliangwang/spark,witgo/spark,JoshRosen/spark,witgo/spark,apache/spark,ueshin/apache-spark,wangyum/spark,WeichenXu123/spark,zero323/spark,zzcclp/spark,JoshRosen/spark,holdenk/spark,ueshin/apache-spark,mahak/spark,vinodkc/spark,vinodkc/spark,dongjoon-hyun/spark,zero323/spark,srowen/spark,hvanhovell/spark,dongjoon-hyun/spark,nchammas/spark,xuanyuanking/spark,nchammas/spark,WeichenXu123/spark,mahak/spark,rednaxelafx/apache-spark,gengliangwang/spark,srowen/spark,xuanyuanking/spark,rednaxelafx/apache-spark,cloud-fan/spark,ueshin/apache-spark,JoshRosen/spark,nchammas/spark,vinodkc/spark,gengliangwang/spark,holdenk/spark,wangyum/spark,hvanhovell/spark,rednaxelafx/apache-spark,hvanhovell/spark,holdenk/spark,WeichenXu123/spark,holdenk/spark,srowen/spark,shaneknapp/spark,zzcclp/spark,mahak/spark,HyukjinKwon/spark,shaneknapp/spark,cloud-fan/spark,JoshRosen/spark,wangyum/spark,zero323/spark,JoshRosen/spark,gengliangwang/spark,xuanyuanking/spark,xuanyuanking/spark,zzcclp/spark,witgo/spark,xuanyuanking/spark,xuanyuanking/spark,wangyum/spark,WeichenXu123/spark,mahak/spark,vinodkc/spark,witgo/spark,mahak/spark,WeichenXu123/spark,nchammas/spark,mahak/spark,HyukjinKwon/spark,apache/spark,gengliangwang/spark,WeichenXu123/spark,JoshRosen/spark,gengliangwang/spark,vinodkc/spark,rednaxelafx/apache-spark,holdenk/spark,wangyum/spark,rednaxelafx/apache-spark,hvanhovell/spark,dongjoon-hyun/spark,apache/spark,vinodkc/spark,witgo/spark,shaneknapp/spark,HyukjinKwon/spark,cloud-fan/spark,dongjoon-hyun/spark,HyukjinKwon/spark,gengliangwang/spark