l10n: Fixed some grammar
l10n: Fixed some grammar

Reported at Transifex.

Signed-off-by: rakekniven <b994f5b47b0f1cbaa874f197776b791d6a9f4484@rakekniven.de>
juliushaertl/deck,nextcloud/deck,juliushaertl/deck,nextcloud/deck,nextcloud/deck,juliushaertl/deck