Updated code comments for clarity based on 2 years

app/workers/prune_old_events_worker.rb

@@ -6,9 +6,8 @@ class PruneOldEventsWorker
 
   # rubocop: disable CodeReuse/ActiveRecord
   def perform
-    # Contribution calendar shows maximum 12 months of events.
-    # Double nested query is used because MySQL doesn't allow DELETE subqueries
-    # on the same table.
+    # Contribution calendar shows maximum 12 months of events, we retain 2 years for data integrity.
+    # Double nested query is used because MySQL doesn't allow DELETE subqueries on the same table.
     Event.unscoped.where(
       '(id IN (SELECT id FROM (?) ids_to_remove))',
       Event.unscoped.where(