fastapi: add dev envs support

Signed-off-by: Milas Bowman <milas.bowman@docker.com>

fastapi/README.md

@@ -52,4 +52,13 @@ Stop and remove the containers
 $ docker compose down
 ```
 
+## Use with Docker Development Environments
 
+You can use this sample with the Dev Environments feature of Docker Desktop.
+
+![Screenshot of creating a Dev Environment in Docker Desktop](../dev-envs.png)
+
+To develop directly on the services inside containers, use the HTTPS Git url of the sample:
+```
+https://github.com/docker/awesome-compose/tree/master/fastapi
+```