## What changes were proposed in this pull request?
API documentation and collaborative filtering documentation page changes to clarify inconsistent description of ALS rank parameter.
- [DOCS] was previously: "rank is the number of latent factors in the model."
- [API] was previously: "rank - number of features to use"
This change describes rank in both places consistently as:
- "Number of features to use (also referred to as the number of latent factors)"
Author: Chris Snow <chris.snowuk.ibm.com>
Author: christopher snow <chsnow123@gmail.com>
Closes#17345 from snowch/SPARK-20011.