Add new hello p5 video to the landing page

### Increasing Access

The new video https://hello.p5js.org/ is a friendly interactive introduction to several p5 features. It is not currently findable from the landing page.

### Most appropriate sub-area of p5.js?

Home

### Feature request details

Adding it, along with a link to the carousel on the main page, has been the main idea; also adding a link to the About page could be useful.