Study how to deliver documentation for extensions

Current situation

The plugins/extensions that are delivered with Qt Creator are documented in the Qt Creator Documentation: https://doc.qt.io/qtcreator/index.html

The plugins/extension that are developed from 3rd parties might be documented in some way by their developers and distributors.

Problem to solve

We plan to deliver extensions as separate packages.

How will we deliver the documentation for those packages to our users?

Possible solutions

• Create separate doc projects for each extension and deliver/publish them as separate doc sets. This is possible with the current tools, but means that we'll have tens of tiny doc sets at doc.qt.io and in Qt Creator Help mode.
• Deliver core documentation with Qt Creator as "Qt Documentation" and publish it at doc.qt.io. Write and deliver extension documentation as .md files that appear in the Extensions mode. This is possible with the current tools, but means that the documentation will appear in two different modes: Help and Extensions