Merge pull request pallets#1022 from jdufresne/hl

Correct syntax highlighting of jinja block in docs

docs/templates.rst

@@ -1350,9 +1350,7 @@ The general syntax is ``<do something> if <something is true> else <do
 something else>``.
 
 The `else` part is optional.  If not provided, the else block implicitly
-evaluates into an undefined object:
-
-.. code-block:: text
+evaluates into an undefined object::
 
     {{ ('[%s]' % page.title) if page.title }}