Add the ability to provide release notes information when an update is available.

[marcocunha]

Diun is working great and I got the notification via Slack. But they look a bit ugly and non informative, like

@channel Docker tag docker.io/library/mariadb:latest updated.
Hostname
c3bd483b5da9
Provider
docker
Created
Feb 11, 2024 23:03:42 UTC
Digest
sha256:a33fbcc7567325096c34d56aa085d69948f5bd0970244b855d4b027e38db083f
Platform
linux/arm64
HubLink
https://github.com/MariaDB/mariadb-docker
CrazyMax © 2024 Diun v4.26.0 | Today at 10:03

If we could add release notes information to this message, that would be great.