fixed markup in doc

diff --git a/doc/intro.rst b/doc/intro.rst
index 18335e1..a0f49a0 100644 (file)
--- a/doc/intro.rst
+++ b/doc/intro.rst
@@ -72,6 +72,8 @@ runtime engine. You can install it like any other PHP extension:
 
 Finally, enable the extension in your ``php.ini`` configuration file:
 
+.. code-block:: ini
+
     extension=twig.so
 
 And from now on, Twig will automatically compiles your templates to take