chore: add comment indicating execution in eCalendar production environment

New_eCalendar/26_前端解析RRULE/26_前端解析RRULE.sql

-# MongoDB 索引
+# MongoDB 索引
@@ -5,6 +5,7 @@ db.events.createIndex(
 )
 
 # SQL 索引
+# eCalendar 线上环境已经执行
 create index idx_device_id_update_time
     on t_user_calendar_categories (device_id, update_time);