Update README.md

README.md

@@ -35,10 +35,19 @@ I co-host a weekly development podcast, [Merge Conflict](http://mergeconflict.fm
 
 ## Version 4 Major Update - Android
 
+We now use Xamarin.Essentials for getting access to the current activity. So ensure you initialize Xamarin.Essentials in your Android app. 
+
+Also if you get a null exception the linker is being aggressive so write the following code in your MainActivity:
+
+```csharp
+var context = Platform.AppContext;
+var activity = Platform.CurrentActivity;
+```
+
 Version 4.X updates to the new Android billing client. This means there are few important changes:
-1.) You must acknowledge all purchases within 3 days, by calling `AcknowledgePurchaseAsync` or the Consume API if it a consumable.
-2.) You must hanle Pending Transactions from outside of you app. See [docs from Google](https://developer.android.com/google/play/billing/integrate#pending)
-3.) `HandleActivityResult` is removed from the API as it is not needed
+1. You must acknowledge all purchases within 3 days, by calling `AcknowledgePurchaseAsync` or the Consume API if it a consumable.
+2. You must hanle Pending Transactions from outside of you app. See [docs from Google](https://developer.android.com/google/play/billing/integrate#pending)
+3. `HandleActivityResult` is removed from the API as it is not needed
 
 ### Pending Transactions:
 * If the result of PurchaseAsync is PurchaseState.PaymentPending, store the order details locally and inform the user that they will have access to the product when the payment completes