[chore] Highlight docs which are draft, WIP, out-of-date, etc.

[andrewnicols]

What do we need to do?

Identify documents in various state in the front-matter and turn this into a page banner with links to contributing to docs, etc.

For example:

---
title: Question bank
draft:
  issueNumber: 99
  trackerIssue: MDL-12345
tags:
  - draft
---

Could be turned into a banner which links to the devdocs issue with information, and the Tracker issue (if relevant), and provides links to the devdocs contributing docs, etc.

Similarly a Draft tag could warn users that this page is a draft and may not be complete, and to see issue # for more information or provide feedback.

[sarjona]

Hi Andrew!

Thanks for raising this! It seems that docusaurus let mark documents as draft using draft: true: facebook/docusaurus#6457

However, when they are marked as draft, they won't be deployed or displayed in the sidebars. So, depending on the page, I think the draft tag is also a great idea (and a good way to identify and find pages to be improved).