Updated documentation.

doc/snac.1

@@ -448,11 +448,11 @@ the notification date
 .It msg
 the full ActivityPub action JSON object
 .It objid
-the object identifier (extracted from message, may be null)
+the object identifier (extracted from msg, may be null)
 .It type
-the action type (extracted from message)
+the action type (extracted from msg)
 .It utype
-the action subtype (extracted from message, may be null)
+the action subtype (extracted from msg, may be null)
 .It uid
 the user identifier (account name)
 .It basedir