(chore): update readme

README.md

@@ -39,7 +39,13 @@ following namespace:
 import { Crossmint } from "crossmint";
 
 const request: Crossmint.CheckoutCreateOrderRequest = {
-    ...
+    payment: {
+        method: Crossmint.EvmPaymentMethods.ArbitrumSepolia,
+        currency: Crossmint.EvmPaymentCurrency.Eth,
+    },
+    lineItems: {
+        collectionLocator: "crossmint:<collectionId>",
+    }
 };
 ```
 
@@ -62,6 +68,15 @@ try {
 }
 ```
 
+Error codes are as followed:
+
+| Status Code | Error Type                 |
+| ----------- | -------------------------- |
+| 400         | `BadRequestError`          |
+| 403         | `ForbiddenError`           | 
+| 404         | `NotFoundError`            |
+| 503         | `ServiceUnavailableError`  |
+
 ## Advanced
 
 ### Retries
@@ -117,6 +132,7 @@ runtimes:
 -   Deno v1.25+
 -   Bun 1.0+
 -   React Native
+-   Browser
 
 ### Customizing Fetch Client