astxml2wiki.xslt: Fix manager event formatting

Manager events were not displaying the "Event: <name>" parameter
in their syntax. This was for two reasons:
 (1) The node type being passed down the element parsing templates
     was 'manager' as opposed to 'managerEvent'. This caused the
     event syntax to be handled as an AMI action, rather than
     an event.
 (2) The managerEventInstance elements were passing attribute @name
     instead of variable $name.

This patch corrects both problems.