iOS Services documentation fatal issue.

**Godot version: Godot 3.3.3:**

**Issue description: Problem with iOS Services**

**URL to the documentation page: https://docs.godotengine.org/en/stable/tutorials/platform/ios/plugins_for_ios.html#plugins-for-ios**

In the documentation about ios services, which describes in-game purchases, there are no very important commands, such as InAppStore.set_auto_finish_transaction(true) and InAppStore.finish_transaction(PRODUCT_ID), that allow you to complete the transaction. Without this, money is withdrawn only for the first purchase, and the rest are free, since the transaction is not completed. This is a very big bug that causes money to be lost. It is imperative to add these two methods in the documentation, since without them all purchases are meaningless. (Translated with the help of a translator, I apologize in advance for any mistakes)