Refactor index.html and dependencies

[bernhold]

The content appearing on the main page for the site (https://github.com/ideas-productivity/ideas-productivity.github.io/blob/main/index.html) is scattered around, making it hard to edit coherently.

The blurb for the hero area is defined in the layout (https://github.com/ideas-productivity/ideas-productivity.github.io/blob/main/_layouts/home.html), and other text is defined in the include (https://github.com/ideas-productivity/ideas-productivity.github.io/blob/main/_includes/_home/hero-home.html).

Maybe we can make this cleaner, so that all of the content for the page is defined in index.html and passed down wherever it is needed below? That include is not currently used anywhere else on the site, so maybe we don't need it as a standalone thing at all?

But what's there now works, so this is not a high priority.