Clarify splitting/passing behaviour for --*-option(s) arguments (#10792)

* Clarify splitting/passing behaviour for --*-option(s) arguments

* Further clarify precise quote parsing behaviour of --*-options options

* Use OPTS, not FLAG, for --repl-options

* Fix typo

* Fix formatting

* Use clearer notation for single and double quotes in docs

This handles geekosaur's review.

* Minor wording change in docs

Co-authored-by: brandon s allbery kf8nh <allbery.b@gmail.com>

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Co-authored-by: brandon s allbery kf8nh <allbery.b@gmail.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>