Please describe your feature request:

Currently, notify only supports the -rl rate limit option which has a max limit of 1 request per second. This is too much for some services such as Microsoft Teams connectors and can cause temporary lockouts. (https://docs.microsoft.com/en-us/microsoftteams/platform/webhooks-and-connectors/how-to/connectors-using?tabs=cURL#rate-limiting-for-connectors)

By adding a -delay flag as well (consisting with other PD tools), we could gain better control over the rate at which notifications are sent and avoid having notifications be temporarily blackholed.

Describe the use case of this feature:

As a user, I need to limit my notifications to not exceed 30 requests per hour. To accomplish this, I could use the flag, -delay 2, to add a 2-second delay between each request.

-delay int             delay between requests in seconds (0 to disable) (default 0)