README.MD is using property webcheckoutdetail in stead of webcheckoutdetailS

[doctordebug]

See the follwing sections

Making a createCheckoutSession request

JSONObject payload = new JSONObject();
JSONObject webCheckoutDetail = new JSONObject();
webCheckoutDetail.put("checkoutReviewReturnUrl", "https://localhost/store/checkout_review");
payload.put("webCheckoutDetail", webCheckoutDetail);

### Making an updateCheckoutSession request


AmazonPayResponse response = null;
JSONObject payload = new JSONObject();
JSONObject updateWebCheckoutDetail = new JSONObject();
updateWebCheckoutDetail.put("checkoutResultReturnUrl", "https://localhost/store/checkout_return");
payload.put("webCheckoutDetail", updateWebCheckoutDetail);

These should be changed to

Making a createCheckoutSession request

JSONObject payload = new JSONObject();
JSONObject webCheckoutDetails = new JSONObject();
webCheckoutDetails.put("checkoutReviewReturnUrl", "https://localhost/store/checkout_review");
payload.put("webCheckoutDetails", webCheckoutDetails);

### Making an updateCheckoutSession request

```java

AmazonPayResponse response = null;
JSONObject payload = new JSONObject();
JSONObject updateWebCheckoutDetails = new JSONObject();
updateWebCheckoutDetails.put("checkoutResultReturnUrl", "https://localhost/store/checkout_return");
payload.put("webCheckoutDetails", updateWebCheckoutDetails);

[bjguillot]

Thanks for the feedback. I think you meant to post this issue into our Checkout V2 SDK GitHub repo: https://github.com/amzn/amazon-pay-api-sdk-java