Renames the "Add plugin" button to "Add Widget"
Renames the "Add plugin" button to "Add Widget"

Signed-off-by: Luís Pereira <95d1463b1ff9eef535e39fb0d755bc242cfcea61@gmail.com>

stefonarch/liblxqt,ThomasVie/liblxqt,pmattern/liblxqt,gilir/liblxqt-qt5,pmattern/liblxqt,stefonarch/liblxqt,rbazaud/liblxqt,lxde/liblxqt,rbazaud/liblxqt,gilir/liblxqt-qt5,ThomasVie/liblxqt,lxde/liblxqt