Adjust language around access tier changes.

Author: wmgries

articles/storage/files/understanding-billing.md

@@ -364,7 +364,7 @@ The following table illustrates the cost breakdown of moving access tiers:
 | **Hot (source)** | <ul><li>1 hot read transaction per file.</li><ul> | -- | <ul><li>1 cool write transaction per file.</li></ul> |
 | **Cool (source)** | <ul><li>1 cool read transaction per file.</li><li>Data retrieval per total used GiB.</li></ul> | <ul><li>1 cool read transaction per file.</li><li>Data retrieval per total used GiB.</li></ul> | -- |
 
-Although there's no formal limit on how often you can change the access tier of your file share, your share will take time to transition based on the amount of data in your share. You can't change the access tier of the share while the file share is transitioning between access tiers. Changing the access tier of the file share doesn't impact regular file share access.
+You can change a file share's access tier up to 5 times within a 30 day window. The first day of the 30 day window begins when the first tier change happens. Changes between access tiers happen instantly, however, once you have changed the access tier of a share, you cannot change it again within 24 hours, even if you have changed the access tier property fewer than 5 times within the last 30 days.
 
 ### Choosing an access tier
 Regardless of how you migrate existing data into Azure Files, we recommend initially creating the file share in transaction optimized access tier due to the large number of transactions incurred during migration. After your migration is complete and you've operated for a few days or weeks with regular usage, you can plug your transaction counts into the [pricing calculator](https://azure.microsoft.com/pricing/calculator/) to figure out which access tier is best suited for your workload.