doc/tutorial/basics: add per-page chapter headings

Change-Id: I9e0a6b5d1a1c820081b3f87c3871068ea042f889
diff --git a/doc/tutorial/basics/lists.md b/doc/tutorial/basics/lists.md
index f70dc1c..d077a06 100644
--- a/doc/tutorial/basics/lists.md
+++ b/doc/tutorial/basics/lists.md
@@ -1,5 +1,7 @@
 [TOC](Readme.md) [Prev](ranges.md) [Next](instances.md)
 
+_Types and Values_
+
 # Lists
 
 Lists define arbitrary sequences of CUE values.