Update lifecycle-management-overview.md

adding cost statement from GA anouncement (https://azure.microsoft.com/en-us/updates/azure-blob-storage-last-access-time-tracking-now-generally-available/)

Author: beber-msft

articles/storage/blobs/lifecycle-management-overview.md

@@ -17,6 +17,8 @@ ms.custom: "devx-track-azurepowershell, references_regions"
 
 Data sets have unique lifecycles. Early in the lifecycle, people access some data often. But the need for access often drops drastically as the data ages. Some data remains idle in the cloud and is rarely accessed once stored. Some data sets expire days or months after creation, while other data sets are actively read and modified throughout their lifetimes. Azure Storage lifecycle management offers a rule-based policy that you can use to transition blob data to the appropriate access tiers or to expire data at the end of the data lifecycle.
 
+Note: Each last access time update is charged as an "other transaction" at most, once every 24 hours per object even if accessed 1000's of times in a day. This is separate from read transactions charges.
+
 With the lifecycle management policy, you can:
 
 - Transition blobs from cool to hot immediately when they're accessed, to optimize for performance.