Specify ZFS datasets dependencies for each service

modules/communication.nix

@@ -51,6 +51,13 @@ in {
     };
   };
 
+  # Start dendrite after config files are mounted
+  systemd.services.dendrite.unitConfig.RequiresMountsFor = [
+    /var/lib/matrix-as-facebook
+    /var/lib/matrix-as-signal
+    /var/lib/matrix-as-telegram
+  ];
+
   # Matrix bridges
   services.matrix-appservices = {
     homeserver = "dendrite";