Add @channel to the slack pager in the alerts manager
Currently we have
title: '[{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] {{ .CommonAnnotations.title }}'
We should probably have
title: '[{{ if eq .Status "firing" }}@channel (dedupe {{ .Alerts.Firing | len }} times) {{ end }}] {{ .CommonAnnotations.title }}'
Or something like this, more data, bringing attention, while making it shorter and easier to understand.