Add variable to disable homeserver url preview

roles/matrix-synapse/defaults/main.yml

@@ -167,6 +167,10 @@ matrix_synapse_password_providers_enabled: false
 # to load message content directly from the homeserver.
 matrix_synapse_push_include_content: true
 
+# If url previews should be generated. This will cause a request from Synapse to
+# URLs shared by users.
+matrix_synapse_url_preview_enabled: true
+
 # Enable exposure of metrics to Prometheus
 # See https://github.com/matrix-org/synapse/blob/master/docs/metrics-howto.rst
 matrix_synapse_metrics_enabled: false