[PATCH] Doc typo fix

[Jesse Weinstein <jessw@xxxxxxxxxxx>]

Small typo I noticed while reading the documentation.

Jesse 

Index: compsys.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/compsys.yo,v
retrieving revision 1.224
diff -u -r1.224 compsys.yo
--- compsys.yo	18 Oct 2009 19:47:31 -0000	1.224
+++ compsys.yo	3 Jan 2010 23:51:16 -0000
@@ -3672,13 +3672,13 @@
 choice of resetting these parameters or propagating changes in them.
 
 A function calling tt(_arguments) with at least
-one action containing a `tt(->)var(string)' therefore must declare
+one action containing a `tt(->)var(string)' must therefore declare
 appropriate local parameters:
 
 example(local context state line
 typeset -A opt_args)
 
-to avoid tt(_arguments) from altering the global environment.
+to prevent tt(_arguments) from altering the global environment.
 )
 item(tt({)var(eval-string)tt(}))(
 vindex(expl, use of)