Document that using Synapse workers with not-matrix-nginx-proxy causes troubles

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2090

docs/configuring-playbook-synapse.md

@@ -42,7 +42,7 @@ matrix_postgres_process_extra_arguments: [
 ]
 ```
 
-If you're using the default setup (the `matrix-nginx-proxy` webserver being enabled) or you're using your own `nginx` server (which imports the configuration files generated by the playbook), you're good to go. If you use some other webserver, you may need to tweak your reverse-proxy setup manually to forward traffic to the various workers.
+**NOTE**: Disabling `matrix-nginx-proxy` (`matrix_nginx_proxy_enabled: false`) (that is, [using your own other webserver](configuring-playbook-own-webserver.md) when running a Synapse worker setup is likely to cause various troubles (see [this issue](https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2090)).
 
 In case any problems occur, make sure to have a look at the [list of synapse issues about workers](https://github.com/matrix-org/synapse/issues?q=workers+in%3Atitle) and your `journalctl --unit 'matrix-*'`.