manager.c: Update AMI Status event documentation

The AMI Status event had linkedid listed twice and was missing the
effective connected line name and number headers.

NOTE: The linkedid and other standard channel snapshot fields in the XML
documentation are part of the <channel_snapshot/> XML template defined in
doc/appdocsxml.xslt.

Change-Id: I004c4c4f9e7b40ef55035c831702721bec82496c