This is just an attempt.  From the second paragraph onwards, the text is
basically fixed, but maybe someone can suggest improvements on the first
paragraph.

Index: LICENCE
===================================================================
RCS file: LICENCE
diff -N LICENCE
--- /dev/null	Tue May  5 21:32:27 1998
+++ LICENCE	Sat Apr  1 20:52:04 2000
@@ -0,0 +1,25 @@
+The Z Shell is copyright (c) 1992-2000 Paul Falstad, Richard Coleman,
+Zoltán Hidvégi, Andrew Main, Peter Stephenson, Sven Wischnowsky, and
+others.  All rights reserved.  Individual authors, whether or not
+specifically named, retain copyright in all changes; in what follows, they
+are referred to as `the Zsh Development Group'.  This is for convenience
+only and this body has no legal status.  The Z shell is distributed under
+the following licence; any provisions made in individual files take
+precedence.
+
+Permission is hereby granted, without written agreement and without
+licence or royalty fees, to use, copy, modify, and distribute this
+software and to distribute modified versions of this software for any
+purpose, provided that the above copyright notice and the following
+two paragraphs appear in all copies of this software.
+
+In no event shall the Zsh Development Group be liable to any party for
+direct, indirect, special, incidental, or consequential damages arising out
+of the use of this software and its documentation, even if and the Zsh
+Development Group have been advised of the possibility of such damage.
+
+The Zsh Development Group specifically disclaim any warranties, including,
+but not limited to, the implied warranties of merchantability and fitness
+for a particular purpose.  The software provided hereunder is on an "as is"
+basis, and the Zsh Development Group have no obligation to provide
+maintenance, support, updates, enhancements, or modifications.