The idea being that hellovulkantriangle demonstrates the same things.
As a getting started tutorial hellovulkanwindow is the ideal example,
but then again QVulkanWindow is not something we want to promote much
in Qt 6.
Some of the docs are moved to hellovulkantriangle.
Pick-to: 6.5
Change-Id: Icbfff70b4a4c7e4c0863a937f3c16038c0b03fbe
Reviewed-by: Christian Strømme <christian.stromme@qt.io>
0e8d347c6a