Adding a note component to address adding DO to existing Worker

Author: Oxyjun

src/content/docs/durable-objects/get-started.mdx

@@ -62,6 +62,15 @@ Move into your new directory:
 cd durable-object-starter
 ```
 
+:::note[Adding a Durable Object to an existing Worker]
+
+To add a Durable Object to an existing Worker, you need to:
+
+- Modify the code of the existing Worker code (as shown in subsequent steps).
+- Update the Wrangler configuration file of your existing Worker to bind the Durable Object to the Worker.
+
+:::
+
 ## 2. Write a Durable Object class using SQL API
 
 Before you create and access a Durable Object, its behavior must be defined by an ordinary exported JavaScript class.