Update ISSUE_TEMPLATE.md

.github/ISSUE_TEMPLATE.md

@@ -1,7 +1,9 @@
-- Bug report or feature request?
+- Bug report or feature request? <!-- Note: sub-optimal but correct code is not a bug -->
 - `uglify-js` version (`uglifyjs -V`)
 - JavaScript input - ideally as small as possible.
 - The `uglifyjs` CLI command executed or `minify()` options used.
 - An example of JavaScript output produced and/or the error or warning.
-
-Note: the release version of `uglify-js` only supports ES5. Those wishing to minify ES6 should use the experimental [`harmony`](https://github.com/mishoo/UglifyJS2#harmony) branch.
+<!--
+    Note: the release version of uglify-js only supports ES5. Those wishing
+    to minify ES6 should use the experimental harmony branch.
+-->