Automated documentation update (#315)

Automated documentation update [skip ci]
Co-authored-by: github-actions <github-actions@github.com>

src/docker-in-docker/README.md

@@ -7,7 +7,7 @@ Create child containers *inside* a container, independent from the host's docker
 
 ```json
 "features": {
-    "ghcr.io/devcontainers/features/docker-in-docker:1": {}
+    "ghcr.io/devcontainers/features/docker-in-docker:2": {}
 }
 ```