Improve discovery error output (#134)

custom_components/localtuya/translations/en.json

@@ -7,7 +7,9 @@
             "cannot_connect": "Cannot connect to device. Verify that address is correct and try again.",
             "invalid_auth": "Failed to authenticate with device. Verify that device id and local key are correct.",
             "unknown": "An unknown error occurred. See log for details.",
-            "entity_already_configured": "Entity with this ID has already been configured."
+            "entity_already_configured": "Entity with this ID has already been configured.",
+            "address_in_use": "Address used for discovery is already in use. Make sure no other application is using it (TCP port 6668).",
+            "discovery_failed": "Something failed when discovering devices. See log for details."
         },
         "step": {
             "user": {