document that mksh evaluates namerefs lazily but ksh93 doesn't

mksh.1

@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.204 2010/01/01 18:02:01 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.205 2010/01/06 18:29:01 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.129 2009/05/28 06:09:06 jmc Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
@@ -71,7 +71,7 @@
 .\" with -mandoc, it might implement .Mx itself, but we want to
 .\" use our own definition. And .Dd must come *first*, always.
 .\"
-.Dd $Mdocdate: January 1 2010 $
+.Dd $Mdocdate: January 6 2010 $
 .\"
 .\" Check which macro package we use
 .\"
@@ -4420,6 +4420,14 @@ in the current scope (this is different from
 .At
 .Nm ksh93 ! )
 instead.
+Also different from
+.At
+.Nm ksh93
+is that
+.Ar value
+is lazily evaluated at the time
+.Ar name
+is accessed.
 This can be used by functions to access variables whose names are
 passed as parametres, instead of using
 .Ic eval .