Docs: Adds set up wizard information

[jonniebigodes]

With this small pull request, the setup page was updated to feature some information about the setup wizard that's enabled when a user installs Storybook.

What was done:

• Updated the wording on the install page and made it conditionally render it.
• Updated the required assets

How to test

1. Follow the steps in the contributing instructions for this branch, docs_add_tour_info

2. Open the documentation, and for React, you'll see:

3. Open the documentation for any other framework and (e.g., Vue) you'll see:

@valentinpalkovic and @cdedreuille, I've requested both of you as reviewers. When you have a moment, take a look and let me know of any feedback. Thanks in advance