updated docs

docs/docs/config/notification.md

@@ -133,18 +133,16 @@ The recommended way to install additional Node.js modules is by running command
 
 As a major enhancement in v3, by default _NotifyBC_ guarantees all subscribers
 of a broadcast push notification will be processed in spite of
-_NotifyBC_ node failures during dispatching. Node failure is a concern because
+node failures during dispatching. Node failure is a concern because
 the time takes to dispatch broadcast push notification is proportional
 to number of subscribers, which is potentially large.
 
 The guarantee is achieved by
 
 1. logging the dispatch result to database individually right after each dispatch
-2. when subscribers are divided into chunks and a chunk sub-request fails, the original request re-submits the sub-request
-3. the original request periodically updates the notification _updated_ timestamp field as heartbeat during dispatching
-4. if original request fails,
-   1. a cron job detects the failure from the stale timestamp, and re-submits the original request
-   2. all chunk sub-requests detects the the failure from the socket error, and stop processing
+2. when subscribers are divided into chunks and a chunk job fails, the job is re-processed by BullMQ
+3. a chunk job updates the notification _updated_ timestamp field as heartbeat
+4. if redis cluster fails, a cron job detects the failure from the stale timestamp, and re-submits the notification request
 
 Guaranteed processing doesn't mean notification will be dispatched to every
 intended subscriber, however. Dispatch can still be rejected by smtp/sms