refactor: add preferAuthorize intent to the README (#16)

Author: brunodesde1987

README.md

@@ -128,7 +128,7 @@ These are the parameteres available on the `launch` method:
 | `externalIdentifier`      | `Optional`      | An optional external identifier that can be supplied. This will automatically be associated to any resource created by Gr4vy and can subsequently be used to find a resource by that ID. |
 | `store`                   | `Optional`       | `'ask'`, `true`, `false` - Explicitly store the payment method or ask the buyer, this is used when a buyerId is provided.|
 | `display`                 | `Optional`       | `all`, `addOnly`, `storedOnly`, `supportsTokenization` - Filters the payment methods to show stored methods only, new payment methods only or methods that support tokenization.
-| `intent`                  | `Optional` | `authorize`, `capture` - Defines the intent of this API call. This determines the desired initial state of the transaction.|
+| `intent`                  | `Optional` | `authorize`, `preferAuthorize`, `capture` - Defines the intent of this API call. This determines the desired initial state of the transaction. When used, `preferAuthorize` automatically switches to `capture` if the selected payment method doesn't support delayed capture.|
 | `metadata`                | `Optional` | An optional dictionary of key/values for transaction metadata. All values should be a string.|
 | `paymentSource`           | `Optional` | `installment`, `recurring` - Can be used to signal that Embed is used to capture the first transaction for a subscription or an installment. When used, `store` is implied to be `true` and `display` is implied to be `supportsTokenization`. This means that payment options that do not support tokenization are automatically hidden. |
 | `cartItems`               | `Optional` | An optional array of cart item objects, each object must define a `name`, `quantity`, and `unitAmount`. Other optional properties are `discountAmount`, `taxAmount`, `externalIdentifier`, `sku`, `productUrl`, `imageUrl`, `categories` and `productType`.|