nurupo authored Mar 21, 2023 and Steve Lhomme committed Mar 27, 2023

HTML help that is shown instead of the plain help text where appropriate
and supported by the interface. The command-line help output and the Qt
GUI plugin tooltips show the plain help text, while the Qt GUI plugin
preferences page displays the HTML help, if available, falling back to
displaying the plain help otherwise.

Allows to present the help text in a more structured and expressive way.
Also useful for out-of-tree plugins, in case they want to link to
plugin's home page, bug tracker, donation page, etc.

For the supported HTML subset, see
https://doc.qt.io/qt-6/richtext-html-subset.html

Fixes #27798