GEODE-6993: Add documentation for alter query-service gfsh command

[DonalEvans]

Co-authored-by: Benjamin Ross bross@pivotal.io
Co-authored-by: Donal Evans doevans@pivotal.io

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[davebarnes97]

Thanks for contributing docs!
A small request: in alter.html.md.erb, in the phrase: "...parsing of the parameter string which makes using..." please add a comma after "string": "...string, which..."

[DonalEvans]

Thanks for contributing docs!
A small request: in alter.html.md.erb, in the phrase: "...parsing of the parameter string which makes using..." please add a comma after "string": "...string, which..."

Done!

[davebarnes97]

The passage that concerned me was deleted along with the option it described.
No further objection, your honor.