[SPARK-18628][ML] Update Scala param and Python param to have quotes

## What changes were proposed in this pull request?

Updated Scala param and Python param to have quotes around the options making it easier for users to read.

## How was this patch tested?

Manually checked the docstrings

Author: krishnakalyan3 <krishnakalyan3@gmail.com>

Closes #16242 from krishnakalyan3/doc-string.

(cherry picked from commit c802ad87)
Signed-off-by: Sean Owen <sowen@cloudera.com>