Better promo images

[WofWca]

This is what it looks like in Chrome Web Store right now:

While pretty, I think it should be more descriptive (of course it shows its description when you hover over it, but that's too much to ask), e.g. add "Skips silence" text. Although Chrome Web Store recommends avoiding text

Also we don't have a "marquee"-size image (1400x560):

Here are the SVGs: https://github.com/WofWca/jumpcutter/blob/0365e0569eaf0544ef439c723d5d2c03d383fed6/src/icons/promo-small.svg

Also if you have an idea for the icon, please share.

Related: #132