Like this https://img.shields.io/github/commits-since/SubtitleEdit/subtitleedit/3.4.7.svg, no idea how to set it for my own specific repo.
Put your GitHub username, repository name, and tag name into the URL like they did.
Here are some examples:
LPGhatguy/postcss-sassy-import:
sk1418/zhuaxia:
@S1U Does it answer your question?
@LPGhatguy @espadrine Yes. Thanks!