res_pjsip: Fix XML typo and update CHANGES.

ASTERISK-24199
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Merged revisions 424528 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 424529 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@424530 65c4cc65-6c06-0410-ace0-fbb531ad65f3