Fix egressFirewall API server example

Author: jwennerberg

modules/nw-egressnetworkpolicy-about.adoc

@@ -55,7 +55,7 @@ spec:
       cidrSelector: <api_server_address_range> <2>
     type: Allow
 # ...
-  - deny:
+  - to:
       cidrSelector: 0.0.0.0/0 <3>
     type: Deny
 ----