[tx-robot] updated from transifex

apps/dav/l10n/sr.js

apps/dav/l10n/sr.json

apps/files_external/l10n/el.js

apps/files_external/l10n/el.json

apps/files_external/l10n/sr.js

apps/files_external/l10n/sr.json

apps/sharebymail/l10n/sr.js

apps/sharebymail/l10n/sr.json

apps/theming/l10n/pl.js

apps/theming/l10n/pl.json

core/l10n/pl.js

core/l10n/pl.json

lib/l10n/el.js

lib/l10n/el.json

settings/l10n/el.js

settings/l10n/el.json