Update Resources/doc/reference/configuration/proxy-client.rst

Co-authored-by: David Buchmann <[email protected]>

Author: jdreesen

Resources/doc/reference/configuration/proxy-client.rst

@@ -405,7 +405,7 @@ configure a service for the ``HttpClient`` and specify that in the
 .. _custom HTTP request factory:
 
 Custom HTTP Request Factory
-------------------
+---------------------------
 
 The proxy client uses an implementation of ``Http\Message\RequestFactory`` to create HTTP requests.
 If you need to customize the request creation, you can configure your custom service and