Note about nesting blocks and {% endblock NAME %}

| Q             | A
| ------------- | ---
| Doc fix?      | [yes]
| New docs?     | [yes] 
| Applies to    | [2.3]
| Fixed tickets | []

Author: ThomasLandauer

book/templating.rst

@@ -370,6 +370,19 @@ When working with template inheritance, here are some tips to keep in mind:
           {{ parent() }}
       {% endblock %}
 
+* Blocks can be nested. For better overview, you can add the block name to the
+  ``{% endblock %}`` tag like so:
+
+  .. code-block:: html+jinja
+
+      {% block foo %}
+          {# ... #}
+          {% block bar %}
+              {# ... #}
+          {% endblock bar %}
+          {# ... #}
+      {% endblock foo %}
+
 .. index::
    single: Templating; Naming conventions
    single: Templating; File locations