plugin/{RepoName}/releaseNotes

Show a plugin's release notes, in whichever form it declared via releaseNotesStyle in its pluginInfo.json (see PLUGININFO_FORMAT.md): gitRelease (latest GitHub Release), gitHistory (commits not yet pulled, read from the plugin's own clone -- no GitHub API call, works for any git-hosted plugin whether or not it tags releases), or script (runs the plugin's own scripts/fpp_releasenotes.sh). none or absent: 404, nothing to show -- the Plugin Manager doesn't offer the icon in that case either, this is just the server-side half of that gate.