add docs for error handling (#174)

* Update README.md

* Update README.md

* Update README.md

Co-authored-by: Alex Vuong <[email protected]>

---------

Co-authored-by: Alex Vuong <[email protected]>

README.md

@@ -84,10 +84,35 @@ const config = {
 
 For more info, refer to the [documentation site](https://salesforcecommercecloud.github.io/commerce-sdk-isomorphic/).
 
+#### `throwOnBadResponse`
+
+When `true`, the SDK throws an `Error` on responses whose status is not 2xx or 304. By default, the value of this flag is `false` for backwards compatibility. Below is an example for accessing the error object via `e.response.json()`.
+
+```js
+const config = {
+  throwOnBadResponse: true
+  // rest of the config object...
+};
+
+const shopperSearch = new ShopperSearch({
+  ...config
+});
+
+// in an async function
+try {
+  const searchResult = await shopperSearch.productSearch({
+    parameters: { q: "shirt" },
+  });
+} catch (e) {
+  const error = await e.response.json();
+  console.log(error);
+  // error is the JSON object - {error: ",,,"}
+}
+```
+
 #### Additional Config Settings
 
 * `headers`: Headers to include with API requests.
-* `throwOnBadResponse`: When `true`, the SDK throws an `Error` on responses whose status is not 2xx or 304.
 
 ### Custom Query Parameters