Move Youtube videos on landing page to dedicated Monarch KG site

[sagehrke]

The YouTube videos on the new landing page (September release) are great, but they are focused on the Monarch-KG as opposed to the Monarch Initiative as a whole. These should move to a page dedicated to the Monarch-KG (perhaps a future about page).

This can be addressed when #776 happens.

[sagehrke]

Option: when these changes are made, we can think about embedding the Monarch Seminar Series youtube videos to our site which are all "introduction to product" videos. They are found here: https://www.youtube.com/@monarchinitiative