'queue add member' help text correction

'queue add member' help text correction

You are adding dial strings to the queue, not channels. An aribitrary string
could be used, but you are typically referencing a channel. Correcting the
command help text.

(issue ASTERISK-22263)
(closes issue ASTERISK-22263)
Reported By: Rusty Newton
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Merged revisions 398884 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 398885 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 398886 from http://svn.asterisk.org/svn/asterisk/branches/12

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@398887 65c4cc65-6c06-0410-ace0-fbb531ad65f3