etcd-website: add emoji warning

Signed-off-by: Wendy Ha <[email protected]>

Author: wendy-ha18

content/en/docs/v3.6/tasks/operator/how-to-migrate.md

@@ -7,7 +7,7 @@ weight: 1200
 `migrate` to transform etcd v2 data model to v3 data model.
 
 {{% alert color="warning" %}}
-**Deprecated functionality:**
+⚠️ **Deprecated functionality:**
 
 The `etcdctl migrate` command was removed in etcd v3.5.0 ([pull/12971](https://github.com/etcd-io/etcd/pull/12971)). If your etcd cluster is already running v3.5 or higher, you can no longer migrate v2 data to v3 using this method.