Update README.md

according to [this GitHub issue](Azure#1854)

README.md

@@ -460,6 +460,10 @@ Azurite will refresh customized account name and key from environment variable e
 
 > Note. Default storage account `devstoreaccount1` will be disabled when providing customized storage accounts.
 
+> Note. When changing storage account name, keep these rules in mind as same as [Azure Storage Account](https://learn.microsoft.com/en-us/azure/storage/common/storage-account-overview#storage-account-name):
+>  - Storage account names must be between 3 and 24 characters in length and may contain numbers and lowercase letters only.
+>  - Your storage account name must be unique within Azurite. No two storage accounts can have the same name.
+
 > Note. The account keys must be base64 encoded string.
 
 > Note. Should update connection string accordingly if using customized account name and key.