Was: Investigate changes in SERVER-62737

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I've encountered internal testing problems where engineers have treated commitQuorum like writeConcern, and not fully understood the difference, as well as in HELP tickets and from support engineers. So I'm improving the internal documentation, and would like a DOCS ticket to similarly improve the external commitQuorum documentation.

I left a comment in the SERVER ticket, and the mongo commit also demonstrates the language change in internal documentation. I think the createIndexes and setIndexCommitQuorum commands could use similar alterations.

(1) https://www.mongodb.com/docs/manual/reference/command/setIndexCommitQuorum/
(2) https://www.mongodb.com/docs/manual/reference/command/createIndexes/

Description of Linked Ticket

There are frequently questions / confusion around commitQuorum not ensuring index builds are available on all/some nodes.

Also potential confusion around voting nodes? Maybe build stalls resultant?