docs: add Chrome for Testing to main README (#1366)

Author: MikeMcC399

README.md

@@ -46,12 +46,17 @@ Cypress officially [supports][Cypress Browser Support] the latest 3 major versio
 <!-- browser links -->
 
 [Chrome]: https://developer.chrome.com/
+[Chrome for Testing]: https://developer.chrome.com/blog/chrome-for-testing
 [Firefox]: https://www.mozilla.org/firefox
 [Firefox Channel Choice]: https://support.mozilla.org/en-US/kb/choosing-firefox-update-channel
 [Edge]: https://developer.microsoft.com/microsoft-edge/
 [Chromium]: https://www.chromium.org/Home/
 [Cypress Browser Support]: https://docs.cypress.io/app/references/launching-browsers#Browser-versions-supported
 
+### Chrome for Testing
+
+[Google Chrome for Testing][Chrome for Testing] is an alternate version of Chrome which is supported by [Cypress 13.17.0](https://docs.cypress.io/app/references/changelog#13-17-0) and above. The [examples/chrome-for-testing](./examples/chrome-for-testing/) directory shows how it can be built into a custom Cypress Docker image.
+
 ### Mozilla geckodriver
 
 [cypress/browsers](./browsers/) and [cypress/included](./included/) images with Firefox `139.0.1` and above are built with the [Mozilla geckodriver](https://github.com/mozilla/geckodriver) included. This driver is needed to test when using Firefox with Cypress versions >= [13.15.1](https://docs.cypress.io/app/references/changelog#13-15-1). The environment variable `GECKODRIVER_PATH` points to the driver located at `/opt/geckodriver/geckodriver`. Earlier images, that do not include the driver, may attempt to download the driver at run-time when testing Firefox, causing failures in air-gapped network environments with no Internet access.