Notifications: show notification on docs from projects marked as delisted

[stsewd]

What's the problem this feature will solve?

When a project is marked as delisted is because it's from an unofficial source, we prevent search engines from indexing those with a custom robots.txt file, but that may take a while to take effect, or the project may be linked from another source. The user reading the documentation isn't aware that the docs have been marked as "unofficial".

Describe the solution you'd like

Show a notification on delisted projects, something like: "This project has been marked as unofficial, the documentation may not be up to date or accurate. Please refer to an official source for the most accurate information."

Alternative solutions

Do nothing

[humitos]

This is probably a good idea.