[FIX] payment_stripe: incorrect flow mentionned in readme

closes odoo/odoo#159788

X-original-commit: 5948e821ce87b78f74150184aa806a43429ae821
Signed-off-by: Valentin Chevalier <vcr@odoo.com>

addons/payment_stripe/README.md

@@ -6,16 +6,26 @@ SDK: [Stripe.js](https://stripe.com/docs/js) version `3`
 
 API: [Stripe API](https://stripe.com/docs/api) version `2019-05-16`
 
-This module integrates Stripe using a custom implementation of the payment with redirection flow: no
-redirect form is rendered and, instead, a Checkout Session object is created from the server before
-the customer is redirected to the session's payment page from the front-end. This is achieved by
-following the [Stripe-hosted page](https://stripe.com/docs/checkout/quickstart) guide.
+This module relies on the Web Elements SDK to render the list of available payment methods and their
+payment detail inputs on the payment form. The JS and CSS assets of the SDK are loaded on the pages
+where the form is visible using a script tag.
+
+When the Web Elements need to fetch/push information from/to Stripe or when a payment operation
+(e.g., refund, offline payment) is executed from the backend, a server-to-server API call is made to
+the appropriate API endpoint.
+
+This is achieved by following the [Collect payment details before creating an Intent]
+(https://docs.stripe.com/payments/accept-a-payment-deferred) guide. It is preferred over the
+recommended "Payment Element" where payment intent is created beforehand because the
+`payment.transaction` object doesn't exist yet when the form is rendered, so we don't have any
+reference to communicate to Stripe. Also, all the methods to create Stripe objects
+(e.g., intents or customers) are defined on the `payment.transaction`​ object.
 
 The module also offers a quick onboarding thanks to the Stripe Connect platform solution.
 
 ## Supported features
 
-- Payment with redirection flow
+- Direct payment flow
 - Webhook notifications
 - Tokenization with or without payment
 - Full manual capture