Explain that you can also use the browsers feature to target older ones (#1221)

* Explain that you can also use the browsers feature to target older ones

* adjust wording

* Update 2018-10-01-create-react-app-v2.md

content/blog/2018-10-01-create-react-app-v2.md

@@ -56,7 +56,7 @@ Run `npm install` (or `yarn`, if you use it). **For many projects, this one-line
 
 Here's a few more tips to get you started.
 
-**When you run `npm start` for the first time after the upgrade,** you'll get a prompt asking about which browsers you'd like to support. Press `y` to accept the default ones. They'll be written to your `package.json` and you can edit them any time. Create React App will use this information to produce smaller CSS bundles if you only target modern browsers.
+**When you run `npm start` for the first time after the upgrade,** you'll get a prompt asking about which browsers you'd like to support. Press `y` to accept the default ones. They'll be written to your `package.json` and you can edit them any time. Create React App will use this information to produce smaller or polyfilled CSS bundles depending on whether you target modern browsers or older browsers.
 
 **If `npm start` still doesn't quite work for you after the upgrade,** [check out the more detailed migration instructions in the release notes](https://github.com/facebook/create-react-app/releases/tag/v2.0.3). There *are* a few breaking changes in this release but the scope of them is limited, so they shouldn't take more than a few hours to sort out. Note that **[support for older browsers](https://github.com/facebook/create-react-app/blob/next/packages/react-app-polyfill/README.md) is now opt-in** to reduce the polyfill size.