Add metric alert slack example with new chart (#5113)

Co-authored-by: Isabel <[email protected]>

Author: 2 people

src/docs/product/integrations/notification-incidents/slack/index.mdx

@@ -73,6 +73,11 @@ Once you receive a Slack notification for an issue alert, you can use the "Resol
 
    ![](slack-alert-message.png)
 
+
+Metric alert Slack notifications include a chart of the metric's status and a link to investigate the alert further:
+
+   ![](slack-metric-alert-message.png)
+
 ### Troubleshooting
 
 #### Rate Limiting Error