Fix docbook installation for doc/kcontrol/kcmlaunchfeedback

rename dir doc/kcontrol/kcmlaunch to doc/kcontrol/kcmlaunchfeedback
scripty automatically generates the correct name for the docmessages catalog, the language docs and the install target

change install target to kcontrol/kcmlaunchfeedback in doc/kcontrol/kcmlaunchfeedback/CMakeLists.txt
english docbook is found by khelpcenter

Differential Revision: https://phabricator.kde.org/D11661