slskd: document common errors/flakiness

hosts/by-name/servo/services/slskd.nix

@@ -3,6 +3,10 @@
 #
 # config precedence (higher precedence overrules lower precedence):
 # - Default Values < Environment Variables < YAML Configuraiton File < Command Line Arguments
+#
+# debugging:
+# - soulseek is just *flaky*. if you see e.g. DNS errors, even though you can't replicate them via `dig` or `getent ahostsv4`, just give it 10 minutes to work out:
+#   - "Soulseek.AddressException: Failed to resolve address 'vps.slsknet.org': Resource temporarily unavailable"
 { config, lib, ... }:
 {
   sane.persist.sys.byStore.plaintext = [