explicit section for old/outdated manuals, which are still informative to some extent;

--- a/doc-src/Dirs	Sun Feb 15 18:56:13 2009 +0100
+++ b/doc-src/Dirs	Sun Feb 15 21:26:25 2009 +0100
@@ -1,1 +1,1 @@
-Ref System Logics HOL ZF Inductive TutorialI IsarOverview IsarRef IsarImplementation Locales LaTeXsugar IsarAdvanced/Classes IsarAdvanced/Codegen IsarAdvanced/Functions
+Intro Ref System Logics HOL ZF Inductive TutorialI IsarOverview IsarRef IsarImplementation Locales LaTeXsugar IsarAdvanced/Classes IsarAdvanced/Codegen IsarAdvanced/Functions

--- a/doc/Contents	Sun Feb 15 18:56:13 2009 +0100
+++ b/doc/Contents	Sun Feb 15 21:26:25 2009 +0100
@@ -6,13 +6,16 @@
   functions       Tutorial on Function Definitions
   codegen         Tutorial on Code Generation
   sugar           LaTeX sugar for proof documents
-  ind-defs        (Co)Inductive Definitions in ZF
 
 Reference Manuals
   isar-ref        The Isabelle/Isar Reference Manual
   implementation  The Isabelle/Isar Implementation Manual
   system          The Isabelle System Manual
+
+Old Manuals (outdated!)
+  intro           Introduction to Isabelle
   ref             The Isabelle Reference Manual
   logics          Isabelle's Logics: overview and misc logics
   logics-HOL      Isabelle's Logics: HOL
   logics-ZF       Isabelle's Logics: FOL and ZF
+  ind-defs        (Co)Inductive Definitions in ZF