flux alerts config is missing required kustomization.yaml updates

[acdoussan]

Went through a bunch of pain trying to set up notifications based off of https://docs.technotim.live/posts/flux-devops-gitops/, turns out the discord-provider/alert files need to be added to the kustomization.yaml resources list for the alert to be actually picked up and created by flux. I don't know if this is supposed to be obvious, but the docs / example should still probably have it.

Were you able to get alerts working without doing this?

refs:

• Flux not creating alert/provider defined in file, only works via CLI fluxcd/notification-controller#494
• https://github.com/techno-tim/launchpad/blob/master/demos/flux-demo/clusters/home/flux-system/kustomization.yaml#L5