## What changes were proposed in this pull request? This PR proposes to improve documentation and fix some descriptions equivalent to several minor fixes identified in https://github.com/apache/spark/pull/15677 Also, this suggests to change `Note:` and `NOTE:` to `.. note::` consistently with the others which marks up pretty. ## How was this patch tested? Jenkins tests and manually. For PySpark, `Note:` and `NOTE:` to `.. note::` make the document as below: **From**      **To**      Author: hyukjinkwon <gurwls223@gmail.com> Closes #15765 from HyukjinKwon/minor-function-doc.
