Update README to describe use of puppeteer on Firefox

README.md

@@ -142,7 +142,7 @@ Other options are documented in [jest-dev-server](https://github.com/smooth-code
 
 Jest Puppeteer automatically detects the best config to start Puppeteer but sometimes you may need to specify custom options. All Puppeteer [launch](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerlaunchoptions) or [connect](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerconnectoptions) options can be specified in `jest-puppeteer.config.js` at the root of the project. Since it is JavaScript, you can use all the stuff you need, including environment.
 
-To run Puppeteer on Firefox using [puppeteer-firefox](https://github.com/GoogleChrome/puppeteer/tree/master/experimental/puppeteer-firefox), you can set `browser` to `firefox`. By default, the value is `chromium` which will use Puppeteer on Chrome.
+To run Puppeteer on Firefox, you can set the `launch.product` property to `firefox`. By default, the value is `chrome` which will use Puppeteer on Chromium.
 
 The browser context can be also specified. By default, the browser context is shared. `incognito` is available if you want more isolation between running instances. More information available in [jest-puppeteer-environment readme](https://github.com/smooth-code/jest-puppeteer/blob/master/packages/jest-environment-puppeteer/README.md)
 
@@ -153,7 +153,6 @@ module.exports = {
     dumpio: true,
     headless: process.env.HEADLESS !== 'false',
   },
-  browser: 'chromium',
   browserContext: 'default',
 }
 ```

packages/jest-environment-puppeteer/README.md

@@ -103,9 +103,6 @@ You can specify a `jest-puppeteer.config.js` at the root of the project or defin
 
 - `launch` <[object]> [All Puppeteer launch options](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerlaunchoptions) can be specified in config. Since it is JavaScript, you can use all stuff you need, including environment.
 - `connect` <[object]> [All Puppeteer connect options](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#puppeteerconnectoptions) can be specified in config. This is an alternative to `launch` config, allowing you to connect to an already running instance of Chrome.
-- `browser` <[string]>. Define a browser to run tests into.
-  - `chromium` Each test uses [puppeteer](https://npmjs.com/package/puppeteer) and runs Chromium
-  - `firefox` Each test uses [puppeteer-firefox](https://npmjs.com/package/puppeteer-firefox) and runs Firefox. This option requires `puppeteer-firefox` as a peer dependency.
 - `browserContext` <[string]>. By default, the browser context (cookies, localStorage, etc) is shared between all tests. The following options are available for `browserContext`:
   - `default` Each test starts a tab, so all tests share the same context.
   - `incognito` Each tests starts an incognito window, so all tests have a separate, isolated context. Useful when running tests that could interfere with one another. (_Example: testing multiple users on the same app at once with login, transactions, etc._)