README.md in apple_receipt-0.2.0 vs README.md in apple_receipt-0.2.1

@@ -9,9 +9,13 @@
 [Status Update Notifications](https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/StoreKitGuide/Chapters/Subscriptions.html#//apple_ref/doc/uid/TP40008267-CH7-SW13).
 These receipts have a different format than [documented](https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Chapters/ValidateLocally.html#//apple_ref/doc/uid/TP40010573-CH1-SW2)
 App Store receipts you might be familiar with, which are [PKCS #7](https://tools.ietf.org/html/rfc2315)
 containers with a payload (receipt data) encoded using [ASN.1](https://www.itu.int/itu-t/recommendations/rec.aspx?rec=X.690).
 
+:warning: Note that this only covers the receipt data (signed data). You should
+not rely on (local) verification for data that is in the notification object, but
+not in the receipt (e.g. `notification_type`).
+
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby