Feature request - add deadline in hours for new referenda

[MathCryptoDoc]

Given the very short time (3h) of recent referendum 232 on Kusama, this would be nice. Estimated time can be calculated fairly precisely from the block difference. Even nicer would be a current time to end when choosing /democracy

[kukabi]

Thanks a lot for the request @MathCryptoDoc! I think it will be simple to add the deadline information to both the /democracy response and the new referendum notification.

I've also been thinking about a notification for validators that haven't voted for referenda that are about to end.

I hope to make some progress regarding this next week.