Docs: Update screenshots?

[melroy89]

I love Mainline Kernels so much! I hope you consider updating your screenshots in your README?

https://github.com/bkw777/mainline/blob/master/6.4_boot_hang_note.jpg

Is that a good idea? Since that will attract new users.

I would also not compress them so much, just use PNG or webp.

Kind regards,
Melroy van den Berg