Allow customising logos

[franky47]

I submitted a project (nuqs) which is part of a larger OSS organisation on GitHub. I'd like to change the logo for that particular project.

An alternative to using the GitHub org avatar would be to allow using the website favicon, but that would cause some issues with the allowed domains for the Next.js image optimisation.

I'd be down to opening a PR to enable this, by switching to a standard <img> tag for non-GitHub avatar URLs. What do you think?