Add FIXME.

Author: dlongley

lib/config.js

@@ -52,6 +52,7 @@ config.ensureConfigOverride.fields.push(meterServiceName);
 cfg.interactions = {
   enabled: false,
   caches: {
+    // FIXME: remove; replace with bedrock-notify
     exchangePolling: {
       // each cache value is only a boolean (the key is ~64 bytes); one entry
       // per exchange being actively polled, 1M = ~60 MiB