Add plugin stability badges (#8198)

* Initial Commit

* Fix plugin library URL

* Need to set plugin library location for prerelease

* Styling tweaks

* Docs

* Add tests that the core plugins all have a valid stability field

plugins/tiddlywiki/codemirror-mode-javascript/plugin.info

@@ -3,5 +3,6 @@
 	"name": "CodeMirror Mode JavaScript",
 	"description": "JavaScript highlighting mode for CodeMirror",
 	"parent-plugin": "$:/plugins/tiddlywiki/codemirror",
-	"list": "readme"
+	"list": "readme",
+	"stability": "STABILITY_2_STABLE"
 }