Add example with random delays for beforeRequest action to readme (#368)

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Author: raurir

README.md

@@ -270,12 +270,19 @@ Should return object which includes custom options for [request](https://github.
 If multiple actions `beforeRequest` added - scraper will use `requestOptions` from last one.
 ```javascript
 // Add ?myParam=123 to querystring for resource with url 'http://example.com'
-registerAction('beforeRequest', ({resource, requestOptions}) => {
+registerAction('beforeRequest', async ({resource, requestOptions}) => {
 	if (resource.getUrl() === 'http://example.com') {
 		return {requestOptions: extend(requestOptions, {qs: {myParam: 123}})};
 	}
 	return {requestOptions};
 });
+
+// Server rejecting a scrape attempt, simply add in some synthetic delays
+registerAction('beforeRequest', async ({ resource, requestOptions }) => {
+	const time = Math.round(Math.random() * 10000);
+	await new Promise((resolve) => setTimeout(resolve, time));
+	return { requestOptions };
+});
 ```
 
 ##### afterResponse