Free text field for info that doesn't fit in an incident

[danny-lloyd]

Add a field to the model to allow a free text field that is displayed at the top of the status page with more general info e.g. making users aware of a new feature or a reminder to update your SSH client for Rocky 9

Could call it a banner/alert in the schema.
Metadata such as 'created on' date, an 'expiry' date. Alert type - enum of info/danger/warning... like in Hinode template

Come up with some use cases...