Enable matrix sliding sync

wellknown/matrix/client

-{"m.homeserver":{"base_url":"https://matrix.tedomum.net"},"m.identity_server":{"base_url":"https://vector.im"},"im.vector.riot.jitsi":{"preferredDomain": "meet.tedomum.net"}}
+{"m.homeserver":{"base_url":"https://matrix.tedomum.net"},"m.identity_server":{"base_url":"https://vector.im"},"org.matrix.msc3575.proxy":{"url":"https://sliding.tedomum.net"}}
\ No newline at end of file