Outdated information regarding the `minifb` crate in `README.md`

[Chubercik]

For example, it occasionally segfaults on some platforms and is missing key features such as the ability to set a window icon. While it would be possible to add these features to minifb, it makes more sense to instead use the standard window handling systems.

While I cannot confirm nor deny the part about segfaults, setting a window icon is very much possible since v0.21 (2022-03-27) and thus shouldn't be listed as one of minifb's downsides.