Status icons use a link for an image to set a project status:

Example:

Not done: https://raw.githubusercontent.com/Orbinuity/.github/main/status/not_done.png

Stable: https://raw.githubusercontent.com/Orbinuity/.github/main/status/stable.png

Unstable: https://raw.githubusercontent.com/Orbinuity/.github/main/status/unstable.png