Add a custom homepage #208

Description:

Currently, the Learn JavaScript GitbookIO opens directly to the Introduction page. There is no separate homepage, and clicking the logo just redirects to the introduction page.

It would improve the user experience to have a dedicated homepage with:
1 . The Learn JavaScript logo prominently displayed

2. Simple animations or visual effects to make it engaging.

3 . A “Let’s Learn” button that redirects users to the Introduction page.

Expected behavior:

1. Users land on a homepage when visiting the site.

2. The homepage displays the logo and some visual enhancements.

3. Clicking “Let’s Learn” takes users to the Introduction page.

4. Clicking the logo also redirects to this homepage.