docs: mention headless chrome

docs/api.md

@@ -580,7 +580,7 @@ This methods attaches Puppeteer to an existing browser instance.
 #### puppeteer.defaultArgs([options])
 
 - `options` <[Object]> Set of configurable options to set on the browser. Can have the following fields:
-  - `headless` <[boolean]> Whether to run browser in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true` unless the `devtools` option is `true`.
+  - `headless` <[boolean]|"chrome"> Whether to run browser in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true` unless the `devtools` option is `true`. "chrome" is a new experimental headless mode (you at your own risk).
   - `args` <[Array]<[string]>> Additional arguments to pass to the browser instance. The list of Chromium flags can be found [here](http://peter.sh/experiments/chromium-command-line-switches/).
   - `userDataDir` <[string]> Path to a [User Data Directory](https://chromium.googlesource.com/chromium/src/+/refs/heads/main/docs/user_data_dir.md).
   - `devtools` <[boolean]> Whether to auto-open a DevTools panel for each tab. If this option is `true`, the `headless` option will be set `false`.
@@ -646,7 +646,7 @@ try {
 - `options` <[Object]> Set of configurable options to set on the browser. Can have the following fields:
   - `product` <[string]> Which browser to launch. At this time, this is either `chrome` or `firefox`. See also `PUPPETEER_PRODUCT`.
   - `ignoreHTTPSErrors` <[boolean]> Whether to ignore HTTPS errors during navigation. Defaults to `false`.
-  - `headless` <[boolean]> Whether to run browser in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true` unless the `devtools` option is `true`.
+  - `headless` <[boolean]|"chrome"> Whether to run browser in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true` unless the `devtools` option is `true`. "chrome" is a new experimental headless mode (you at your own risk).
   - `channel` <[string]> When specified, Puppeteer will search for the locally installed release channel of Google Chrome and use it to launch. Available values are `chrome`, `chrome-beta`, `chrome-canary`, `chrome-dev`. When channel is specified, `executablePath` cannot be specified.
   - `executablePath` <[string]> Path to a browser executable to run instead of the bundled Chromium. If `executablePath` is a relative path, then it is resolved relative to [current working directory](https://nodejs.org/api/process.html#process_process_cwd). **BEWARE**: Puppeteer is only [guaranteed to work](https://github.com/puppeteer/puppeteer/#q-why-doesnt-puppeteer-vxxx-work-with-chromium-vyyy) with the bundled Chromium, use at your own risk.
   - `slowMo` <[number]> Slows down Puppeteer operations by the specified amount of milliseconds. Useful so that you can see what is going on.