[plasmashell] Update docs for panelTakesFocus to make it generic
Summary:
We want surfaces with a notification role to be able to switch ability
to take focus or not on the fly. The semantics are identical as the
panel
taking focus, we may as well re-use what exists and remove the implicit
limitation than re-invent the wheel and complicate things.
Test Plan: Docs
Reviewers: KWin, romangg
Reviewed By: KWin, romangg
Subscribers: romangg, apol, kde-frameworks-devel
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D26175