* Improve the type for callbacks registered by extensions
The previous type was CanMakePaymentCallback, used for the payment methods's own canMakePayment callbacks, which could also return Promises. In order to eliminate the confusion, a new type has been created that defines callbacks that only return true or false.
* Document registerPaymentMethodExtensionCallbacks
* Update docs/extensibility/filtering-payment-methods.md
Co-authored-by: Thomas Roberts <5656702+opr@users.noreply.github.com>
* Add information about payment method name in documentation
Co-authored-by: Thomas Roberts <5656702+opr@users.noreply.github.com>