fix spelling in QMP sub directory

Cc: Markus Armbruster <armbru@redhat.com>
Acked-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NDong Xu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

QMP/qmp-events.txt

@@ -126,7 +126,7 @@ the authentication ID is not provided.
 VNC_DISCONNECTED
 ----------------
 
-Emitted when the conection is closed.
+Emitted when the connection is closed.
 
 Data: