Content Editor Popup for GA

Problem:

The Rich Text Editor will be rolling out across GitLab wherever Markdown is available (more information can be found here on rollout structure).

As this feature impacts users across the platform, in what we assume is an overwhelmingly positive way, we want to ensure folks are aware of where to find it, how to activate it, and how to utilize it. As a result of the scale of GitLab it can be easy for new and valuable features to be lost in the fold of monthly releases.

Proposal:

Our Proposal, in groupknowledge, is to create a simple popup for users that highlights the new switcher element (detailed here), tells them what it does, and encourages them to try it out. This would be similar to the structure of the popup for when the new Web IDE was rolled out.