Add theme support to add features on landing page

[Thecarisma]

Add theme feature to add landing page features so website is not just bland basic ugly looking documentation website.
E.g. https://www.jetbrains.com/pycharm-edu/

Possible configurations

html_theme_options = {
    landing_page_items: {
        section_one: [
              #... 
         ]
    }
}

Be creative