Add Slack and mail receiver to AlertManager config

Change-Id: Ib82ef0a7d029f84a7f92a90384bac02a0870b521
diff --git a/README.rst b/README.rst
index 4c126b5..c1f4498 100644
--- a/README.rst
+++ b/README.rst
@@ -121,6 +121,18 @@
             webhook_configs:
               - url: http://127.0.0.1
                 send_resolved: true
+          - name: 'HTTP-slack'
+            slack_configs:
+              - api_url: http://127.0.0.1/slack
+                send_resolved: true
+          - name: 'smtp'
+            email_configs:
+              - to: test@example.com
+                from: test@example.com
+                smarthost: example.com
+                auth_username: username
+                auth_password: password
+                send_resolved: true
 
 Configure pushgateway
 ---------------------