Add missing descriptions on the trashcan and appmenubar plasmoids
Summary:
Was missing, error appstreamtest and appeared empty on the Widget
explorer.
Reviewers: davidedmundson, Plasma, broulik
Reviewed By: davidedmundson, Plasma, broulik
Subscribers: broulik, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D4205