[SPARK-15702][DOCUMENTATION] Update document programming-guide accumulator section

## What changes were proposed in this pull request?

Update document programming-guide accumulator section (scala language)
java and python version, because the API haven't done, so I do not modify them.

## How was this patch tested?

N/A

Author: WeichenXu <WeichenXu123@outlook.com>

Closes #13441 from WeichenXu123/update_doc_accumulatorV2_clean.