[BUG] Document overriding the spark rapids jar in docker image and name used

[tgravescs]

Describe the bug
Using the released docker image with the Job Workflow options in databricks, the Spark UI doesn't load. It first goes to the master UI and then if still try to click through to the application UI, it gives a bad gateway.

[tgravescs]

it turns out I had conflicting spark rapids jars. not sure why this caused UI issues but it did.
We should document how to properly override the spark rapids jar in the docker image.

[tgravescs]

the docker image has the jar at /databricks/jars/rapids-4-spark_2.12-22.10.0-cuda11.jar The dockerfile in this repo has default as rapids-4-spark_2.12-22.10.0.jar

[tgravescs]

so to override the jar file the user would just need to specify their own init script and then add lines like:

They would want to start with the script file:/opt/spark-rapids/init.sh (see https://github.com/NVIDIA/spark-rapids-container/tree/dev/Databricks)

and then add lines like:

rm -f /databricks/jars/rapids-4-spark_*
cp /dbfs/user/foo/rapids-4-spark_2.12-22.12.0-SNAPSHOT-cuda11-something.jar /databricks/jars