## What changes were proposed in this pull request?

This issue aims to fix some errors in R examples and make them up-to-date in docs and example modules.

- Remove the wrong usage of `map`. We need to use `lapply` in `sparkR` if needed. However, `lapply` is private so far. The corrected example will be added later.
- Fix the wrong example in Section `Generic Load/Save Functions` of `docs/sql-programming-guide.md` for consistency
- Fix datatypes in `sparkr.md`.
- Update a data result in `sparkr.md`.
- Replace deprecated functions to remove warnings: jsonFile -> read.json, parquetFile -> read.parquet
- Use up-to-date R-like functions: loadDF -> read.df, saveDF -> write.df, saveAsParquetFile -> write.parquet
- Replace `SparkR DataFrame` with `SparkDataFrame` in `dataframe.R` and `data-manipulation.R`.
- Other minor syntax fixes and a typo.

## How was this patch tested?

Manual.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #12649 from dongjoon-hyun/SPARK-14883.