Add pickup event to AMI. Also, fix AMI documentation.

(closes issue #16431)
 Reported by: syspert
 Patches: 
       20100112__issue16431.diff.txt uploaded by tilghman (license 14)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@240421 65c4cc65-6c06-0410-ace0-fbb531ad65f3