tuned header

--- a/src/HOL/Library/Fset.thy	Tue Oct 05 18:09:31 2010 +0200
+++ b/src/HOL/Library/Fset.thy	Wed Oct 06 13:48:12 2010 +0200
@@ -1,7 +1,7 @@
 
 (* Author: Florian Haftmann, TU Muenchen *)
 
-header {* Executable finite sets *}
+header {* A set type which is executable on its finite part *}
 
 theory Fset
 imports More_Set More_List