[feature] Notification - Add URL to changedetection.io webpage

[N1c093]

First of all, thank you for this project.

I'm currently using a lot of notifications, these are working pretty fine.
It would be great, if you can add an URL for the webpage/UI to the notification. So you can easily navigate to the webui after you receive anotification.
Maybe it would be good to set these URL on the settingspage or as a docker variable.

Thank you in advance.

[dgtlmoon]

See latest docker image :)

[N1c093]

Thank you for the rapid implementation 👍