Restructure exampleSite once again, improve sections and flow

exampleSite/content.en/docs/content/shortcodes/section.md

@@ -0,0 +1,18 @@
+---
+bookHidden: true
+---
+
+# Section
+
+Render child pages of the current section as a definition list with titles and descriptions.
+
+## Syntax
+
+```tpl
+{{</* section [summary] */>}}
+```
+
+## Parameters
+
+`summary`
+: When present, includes the page summary below each title.