Registers a new subscriber to the notification service with an HTTPS webhook.
The following example registers a new HTTPS webhook subscriber to the Notification Service.
efa notification subscribers add-https --url https://path/to/my/service:port 
--username myusername --password mypassword --insecure
Successfully registered subscriber.
+-----------+-----------------------------------------------------------------------+
| attribute | value                                                                 |
+-----------+-----------------------------------------------------------------------+
| id        | 1                                                                     |
+-----------+-----------------------------------------------------------------------+
| handler   | http                                                                  |
+-----------+-----------------------------------------------------------------------+
| endpoint  | https://path/to/my/service:port                                     |
+-----------+-----------------------------------------------------------------------+
| config    | {"cacert":"","insecure":true,"password":"mypassword",
              "username":"myusername"}                                              |
+-----------+-----------------------------------------------------------------------+
Notification Subscriber ID=1
--- Time Elapsed: 2.203878641s ---