Fix formatting

Author: ADmad

en/appendices/5-3-migration-guide.rst

@@ -34,8 +34,8 @@ Deprecations
 Http
 ----
 
-- Using `$request->getParam('?')` to get the query params is deprecated.
-  Use `$request->getQueryParams()` instead.
+- Using ``$request->getParam('?')`` to get the query params is deprecated.
+  Use ``$request->getQueryParams()`` instead.
 
 ORM
 ---