Update controller.rst

Co-authored-by: Oskar Stark <oskarstark@googlemail.com>

Author: dbu

controller.rst

@@ -505,7 +505,7 @@ payload formats::
 .. tip::
 
     If you write a JSON API, make sure to declare your route to use the JSON
-    format. This will make the error handling output a json response in case of
+    format. This will make the error handling output a JSON response in case of
     validation errors, rather than an HTML page.
 
     ``#[Route('/dashboard', name: 'dashboard', format: 'json')]