reorder chapters for generated document

--- a/src/HOLCF/ROOT.ML	Wed Nov 10 18:30:17 2010 -0800
+++ b/src/HOLCF/ROOT.ML	Wed Nov 10 18:37:11 2010 -0800
@@ -6,4 +6,4 @@
 
 no_document use_thys ["Nat_Bijection", "Countable"];
 
-use_thys ["HOLCF"];
+use_thys ["Plain_HOLCF", "Fixrec", "HOLCF"];