5.0.3: CLI documentation (rebased onto develop)


This is the same as gh-868 but rebased onto develop.

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This PR addresses several CLI documentation needs summarized in https://trello.com/c/AmB1db6W/57-5-0-3-documentation-fixes.

                
I don't know what "all command accepting command arguments" might mean. It's not just "commands accepting arguments" is it? (I am guessing that "command-accepting" isn't an adjectival phrase.)