Add video to readme

[thijstriemstra]

Is it ok to add https://www.youtube.com/watch?v=YWE1LgwQbbQ to the readme, if so, I'll open a PR for it.

[corrados]

This is what is the intention of the pinned discussion thread: https://github.com/corrados/edrumulus/discussions/28

[corrados]

I have now added a gallery page similar to what open-e-drums does on their page https://open-e-drums.com/gallery.html.

https://github.com/corrados/edrumulus/blob/main/doc/gallery.md

[thijstriemstra]

thanks!