Mention Docker support in "Building for Multiple Platforms"

I remember Qt Creator has support for building code in a virtual machine. But browsing the documentation, I couldn't find it at first, until I hit:

Adding Docker Devices

I suggest to advertise this more prominently.

• The page could be linked from Building for Multiple Platforms – the first page I was navigating to when thinking about this.
• The page could also be linked from Embedded Platforms. For instance in the Remote Linux section, where it currently says "You must have a tool chain for building applications for embedded Linux devices installed on the development PC."

Furthermore, https://doc.qt.io/qtcreator/creator-connecting-mobile.html only mentions Docker images as a way to '"run, debug, and analyze applications". The actual page then explains though that the docker support is also about building applications.