fix typos

CHANGES.rst

@@ -7,15 +7,16 @@ Added support for the ``Content-Range`` HTTP header in the GET endpoint of
 ``PiccoloCRUD``. This means the API client can fetch the number of available
 rows, without doing a separate API call to the ``count`` endpoint.
 
-```
-GET /?__range_header=true
-```
+.. code-block::
+
+  GET /?__range_header=true
 
 If the page size is 10, then the response header then looks something like:
 
-```
-Content-Range: movie 0-9/100
-```
+.. code-block::
+
+  Content-Range: movie 0-9/100
+
 
 The feature was created to make Piccolo APIs work better with front ends like
 `React Admin <https://marmelab.com/react-admin/>`_.