message: Fix async await syntax in README
diff: @@ -15,7 +15,7 @@ Registering a Web Pixels Extension:
  ```js
  import {register} from '@shopify/web-pixels-extension';
  -register(({configuration, analytics, browser}) => {
  +register(async ({configuration, analytics, browser}) => {
  const origin = await browser.origin.get();
  window.my_pixel.configure({
  