ari wiki docs: add notes about allowMultiple parameters.

This patch adds a note to any parameter that has 'allowMultiple' set in
the Swagger documentation.

(closes issue ASTERISK-22704)
........

Merged revisions 402367 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@402368 65c4cc65-6c06-0410-ace0-fbb531ad65f3