clarified doc sections: add-on components may focus their own application name;

--- a/doc/Contents	Thu Dec 06 00:24:21 2018 +0100
+++ b/doc/Contents	Thu Dec 06 12:55:53 2018 +0100
@@ -1,4 +1,4 @@
-Tutorials!
+Isabelle Tutorials!
   prog-prove      Programming and Proving in Isabelle/HOL
   locales         Tutorial on Locales
   classes         Tutorial on Type Classes
@@ -11,14 +11,14 @@
   eisbach         The Eisbach User Manual
   sugar           LaTeX Sugar for Isabelle documents
 
-Reference Manuals!
+Isabelle Reference Manuals!
   main            What's in Main
   isar-ref        The Isabelle/Isar Reference Manual
   implementation  The Isabelle/Isar Implementation Manual
   system          The Isabelle System Manual
   jedit           Isabelle/jEdit
 
-Old Manuals
+Old Isabelle Manuals
   tutorial        Tutorial on Isabelle/HOL
   intro           Old Introduction to Isabelle
   logics          Isabelle's Logics: HOL and misc logics

--- a/src/Pure/Tools/doc.scala	Thu Dec 06 00:24:21 2018 +0100
+++ b/src/Pure/Tools/doc.scala	Thu Dec 06 12:55:53 2018 +0100
@@ -52,7 +52,7 @@
   private val Doc_Entry = new Regex("""^\s+(\S+)\s+(.+)\s*$""")
 
   private def release_notes(): List[Entry] =
-    Section("Release notes", true) ::
+    Section("Release Notes", true) ::
       Path.split(Isabelle_System.getenv_strict("ISABELLE_DOCS_RELEASE_NOTES")).flatMap(text_file(_))
 
   private def examples(): List[Entry] =