Docs: Refactor contact points section of alerting docs (#49758)

* Initial commit

* weight adjustments

* Checkin changes.

docs/sources/alerting/contact-points/message-templating/example-template.md

@@ -0,0 +1,67 @@
+---
+aliases:
+  - /docs/grafana/latest/alerting/contact-points/message-templating/
+  - /docs/grafana/latest/alerting/message-templating/
+  - /docs/grafana/latest/alerting/unified-alerting/message-templating/
+keywords:
+  - grafana
+  - alerting
+  - guide
+  - contact point
+  - templating
+title: Example message template
+weight: 115
+---
+
+# Example of a custom template
+
+Here's an example of how to use a custom template. You can also use the default template included in the setup.
+
+Step 1: Configure a template to render a single alert.
+
+```
+{{ define "myalert" }}
+  [{{.Status}}] {{ .Labels.alertname }}
+
+  Labels:
+  {{ range .Labels.SortedPairs }}
+    {{ .Name }}: {{ .Value }}
+  {{ end }}
+
+  {{ if gt (len .Annotations) 0 }}
+  Annotations:
+  {{ range .Annotations.SortedPairs }}
+    {{ .Name }}: {{ .Value }}
+  {{ end }}
+  {{ end }}
+
+  {{ if gt (len .SilenceURL ) 0 }}
+    Silence alert: {{ .SilenceURL }}
+  {{ end }}
+  {{ if gt (len .DashboardURL ) 0 }}
+    Go to dashboard: {{ .DashboardURL }}
+  {{ end }}
+{{ end }}
+```
+
+Step 2: Configure a template to render entire notification message.
+
+```
+{{ define "mymessage" }}
+  {{ if gt (len .Alerts.Firing) 0 }}
+    {{ len .Alerts.Firing }} firing:
+    {{ range .Alerts.Firing }} {{ template "myalert" .}} {{ end }}
+  {{ end }}
+  {{ if gt (len .Alerts.Resolved) 0 }}
+    {{ len .Alerts.Resolved }} resolved:
+    {{ range .Alerts.Resolved }} {{ template "myalert" .}} {{ end }}
+  {{ end }}
+{{ end }}
+```
+
+Step 3: Add `mymessage` in the notification message field.
+
+```
+Alert summary:
+{{ template "mymessage" . }}
+```