fixed document

--- a/src/HOLCF/ROOT.ML	Sun Feb 15 11:26:38 2009 +0100
+++ b/src/HOLCF/ROOT.ML	Sun Feb 15 11:34:46 2009 +0100
@@ -5,4 +5,6 @@
 HOLCF -- a semantic extension of HOL by the LCF logic.
 *)
 
+no_document use_thy "Nat_Int_Bij";
+
 use_thy "HOLCF";