Remove cssclass from admonition

Author: nlarew

source/services.txt

@@ -61,9 +61,9 @@ You can also create :ref:`incoming webhooks <service-webhooks>` that
 enable external services to communicate directly with your {+app+}
 over HTTP.
 
-.. cssclass:: note
 .. admonition:: Built-In Service Clients
-
+   :class: note
+   
    {+service+} includes clients for certain external services, such
    as :doc:`Twilio </services/twilio>` and :doc:`AWS </services/aws>`.
    You can also use the :doc:`HTTP service </services/http>` to create a