docs(README): add a debugging section (#2467)

README.md

@@ -194,7 +194,27 @@ Explore the [API documentation](docs/api.md) and [examples](https://github.com/G
 
         await page.evaluate(() => console.log(`url is ${location.href}`));
 
-4. Enable verbose logging - All public API calls and internal protocol traffic
+4. Stop test execution and use a debugger in browser
+
+  - Use `{devtools: true}` when launching Puppeteer:
+
+      `const browser = await puppeteer.launch({devtools: true});`
+
+  - Change default test timeout:
+
+      jest: `jest.setTimeout(100000);`
+
+      jasmine: `jasmine.DEFAULT_TIMEOUT_INTERVAL = 100000;`
+
+      mocha: `this.timeout(100000);` (don't forget to change test to use [function and not '=>'](https://stackoverflow.com/a/23492442))
+
+  - Add an evaluate statement with `debugger` inside / add  `debugger` to an existing evaluate statement:
+
+    `await page.evaluate(() => {debugger;});`
+
+     The test will now stop executing in the above evaluate statement, and chromium will stop in debug mode.
+
+5. Enable verbose logging - All public API calls and internal protocol traffic
    will be logged via the [`debug`](https://github.com/visionmedia/debug) module under the `puppeteer` namespace.
 
         # Basic verbose logging