qapi: fix example of query-vnc command

Example output has an extra ',' delimiter in member "websocket" and it
lacks it in "family" member. Fix it.

Problem was noticed when trying to load the example into python's json
library.

Signed-off-by: Victor Toso <victortoso@redhat.com>
Message-Id: <20220901085840.22520-3-victortoso@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

qapi/ui.json

@@ -667,8 +667,8 @@
 #             {
 #                "host":"127.0.0.1",
 #                "service":"50401",
-#                "family":"ipv4"
-#                "websocket":false,
+#                "family":"ipv4",
+#                "websocket":false
 #             }
 #          ]
 #       }