README doesn't work well with dark mode github

[dhalucario]

[draeder]

I added some images to the repo to support dark mode. I need to do some testing before updating the readme.

[draeder]

Well, I can confirm the image looks good in dark mode, but with markup, the hash doesn't change which one is displayed. And with markdown, the image can't be centered. :(

[chr15m]

Could just add a white background to the image.

[dhalucario]

I'd recommend going after Telegrams design recommendation for stickers and add a border:

Looks like before on white backgrounds and on dark backgrounds its clearly visible