docs: pl/container updates - plcontainer command, configuration file (#4223)

*  docs: pl/container updates - plcontainer command, configuration file

-removed experimental warning.
-replaced plcontainer command with new options.
-updated configuration file - changed element names, added setting element.
-updated default shared volume.

PR for 5X_STABLE
Will be ported to MAIN

* docs: pl/container - updates based on review comments.

* docs: pl/container - more updates based on additional review comments.

* docs: pl/container - minor edit

* docs: pl/container - another minor fix.