Update the website so as to sell Helix's key features

[gyreas]

helix-editor/helix#4419 (comment)

Can we highlight the new way of editing, select-act model, on the website? This way new users can tell what's different from vim/emacs. Update the video to show each of those features in use as well.

I'm willing to submit the video if that's gonna work.

[0atman]

Thanks for your work on Helix folks, though I disagree on the keybindings decision, what you are building is nothing short of Herculean!