Provide same info as in spark-submit --help

this is stated for --packages and --repositories. Without stating it for --jars, people expect a standard java classpath to work, with expansion and using a different delimiter than a comma. Currently this is only state in the --help for spark-submit "Comma-separated list of local jars to include on the driver and executor classpaths."

Author: James Lohse <jimlohse@users.noreply.github.com>

Closes #10890 from jimlohse/patch-1.