how to use bootstrap cdn in gatsby code example

Example 1: add bootstrap to gatsby

npm install --save react-bootstrap
npm install --save bootstrap

Example 2: add bootstrap to gatsby

import React from 'react';
import { Button } from 'react-bootstrap';

const MyComponent = () => (
      <div>
        <p>This contains a button which is exported by react-bootstrap</p>
        <Button variant="primary">Primary</Button>
    </div>
);