docs: update bootstrap section to use v4

Closes facebook#3308

Author: TheSharpieOne

Diff for: packages/react-scripts/template/README.md

@@ -841,18 +841,18 @@ Alternatively, you can force the linter to ignore any line by adding `// eslint-
 
 ## Adding Bootstrap
 
-You don’t have to use [React Bootstrap](https://react-bootstrap.github.io) together with React but it is a popular library for integrating Bootstrap with React apps. If you need it, you can integrate it with Create React App by following these steps:
+You don’t have to use [reactstrap](https://reactstrap.github.io/) together with React but it is a popular library for integrating the latest version of Bootstrap with React apps. If you need it, you can integrate it with Create React App by following these steps:
 
-Install React Bootstrap and Bootstrap from npm. React Bootstrap does not include Bootstrap CSS so this needs to be installed as well:
+Install reactstrap and Bootstrap from npm. reactstrap does not include Bootstrap CSS so this needs to be installed as well:
 
 ```sh
-npm install --save react-bootstrap bootstrap@3
+npm install --save reactstrap bootstrap
 ```
 
 Alternatively you may use `yarn`:
 
 ```sh
-yarn add react-bootstrap bootstrap@3
+yarn add reactstrap bootstrap
 ```
 
 Import Bootstrap CSS and optionally Bootstrap theme CSS in the beginning of your ```src/index.js``` file:
@@ -864,13 +864,13 @@ import 'bootstrap/dist/css/bootstrap-theme.css';
 // components takes precedence over default styles.
 ```
 
-Import required React Bootstrap components within ```src/App.js``` file or your custom component files:
+Import required reactstrap components within ```src/App.js``` file or your custom component files:
 
 ```js
-import { Navbar, Jumbotron, Button } from 'react-bootstrap';
+import { Navbar, Jumbotron, Button } from 'reactstrap';
 ```
 
-Now you are ready to use the imported React Bootstrap components within your component hierarchy defined in the render method. Here is an example [`App.js`](https://gist.githubusercontent.com/gaearon/85d8c067f6af1e56277c82d19fd4da7b/raw/6158dd991b67284e9fc8d70b9d973efe87659d72/App.js) redone using React Bootstrap.
+Now you are ready to use the imported reactstrap components within your component hierarchy defined in the render method. Here is an example [`App.js`](https://gist.githubusercontent.com/TheSharpieOne/fd2b1c7de92f0f442b8692a9c9aa6d3c/raw/57ecd212edd56e2114e4854d21174d6132cf1a0f/App.js) redone using reactstrap.
 
 ### Using a Custom Theme