## What changes were proposed in this pull request?

Removing references to assembly jar in documentation.
Adding an additional (previously undocumented) usage of spark-submit to run examples.

## How was this patch tested?

Ran spark-submit usage to ensure formatting was fine. Ran examples using SparkSubmit.

Author: Mark Grover <mark@apache.org>

Closes #12365 from markgrover/spark-14601.