Write page templates and canonical examples.

Conflicts:
	_data/tasks.yml
	_data/tutorials.yml
	docs/tasks/access-kubernetes-api/http-proxy-access-api.md
	docs/tasks/index.md
	docs/tutorials/index.md

_includes/templates/concept.md

@@ -0,0 +1,32 @@
+{% if overview %}
+
+{{ overview }}
+
+{% else %}
+
+{% include templates/_errorthrower.md missing_block='overview' purpose='provides an overview of this concept.' %}
+
+{% endif %}
+
+* TOC
+{:toc}
+
+{% if body %}
+
+{{ body }}
+
+{% else %}
+
+{% include templates/_errorthrower.md missing_block='body' purpose='supplies the body of the page content.' %}
+
+{% endif %}
+
+
+{% if whatsnext %}
+
+### What's next
+
+{{ whatsnext }}
+
+{% endif %}
+