DataSchema docs page is incomplete

[GalOshri]

The DataSchema API Reference page is missing some of the parameters shown in the Data Schema concept page.

For example, the concept page shows how to modify the names of the columns in .read_schema() but this is not shown in the API reference.

[montebhoover]

@ganik Do we want to track issues like this in https://github.com/MicrosoftDocs/mlnet-pr/issues ?