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

Change-Id: I9e0a6b5d1a1c820081b3f87c3871068ea042f889
diff --git a/doc/tutorial/basics/foldany.md b/doc/tutorial/basics/foldany.md
index f24097e..dd77606 100644
--- a/doc/tutorial/basics/foldany.md
+++ b/doc/tutorial/basics/foldany.md
@@ -1,5 +1,7 @@
 [TOC](Readme.md) [Prev](fold.md) [Next](comments.md)
 
+_JSON Sugar and other Goodness_
+
 # Folding all Fields
 
 This also works if a struct has more than one member.