Feature summary:
CodeMirror's syntax highlighting is offered at all WMF-hosted wikis in the 2010 and 2017 wikitext editors. This is a request to alert editors to the existence of the option.

Use case(s):
As an experienced editor, I rarely look at the buttons in the wikitext editors' toolbars. As a result, new features can be added without me noticing that they are present. Additionally, in this case, the icon in the toolbar is not entirely intuitive (T174145). I want new features to be shown to me, so that I can decide for myself whether I want to use them.

Presumably, in the 2017WTE, this would involve adding another glowing blue dot (as already happens with the link and cite buttons). Ideally, this notice would appear once and never bother me again.

Benefits:
More people can use this tool, when/if it works for them. Other people will learn how to turn it off, which will be particularly helpful if they ever solve the problems and T288161: Enable CodeMirror's Syntax Highlighting on English Wikipedia by default.