Pontoon: Update Welsh (cy) localization of WebThings Gateway
Pontoon: Update Welsh (cy) localization of WebThings Gateway

Localization authors:
- Rhoslyn Prys <rprys@posteo.net>

moziot/gateway,moziot/gateway,mozilla-iot/gateway,mozilla-iot/gateway,mozilla-iot/gateway,moziot/gateway,mozilla-iot/gateway,mozilla-iot/gateway