add description for -e argument (for ktruss)

usr.bin/ktrace/ktrace.1

@@ -1,4 +1,4 @@
-.\"	$NetBSD: ktrace.1,v 1.12 1999/07/28 01:56:06 enami Exp $
+.\"	$NetBSD: ktrace.1,v 1.13 2000/04/10 08:11:01 jdolecek Exp $
 .\"
 .\" Copyright (c) 1990, 1993
 .\"	The Regents of the University of California.  All rights reserved.
@@ -139,6 +139,10 @@ trace context switches
 .It Cm + 
 trace the default set of trace points (c, e, n, i, s)
 .El
+.It Fl e Ar emulation
+If an emulation of a process is unknown, 
+interpret system call maps assuming the named emulation instead of
+default "netbsd".
 .It Ar command
 Execute
 .Ar command