docs(docker): correct the image's 'and nothing else' contents claim

The README opened by saying the image packages the CLI 'and nothing else',
which the driver install one commit earlier makes false. Both the README
and the Dockerfile header now name what is actually inside.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016yfqQh2dBgPAymYd7xipza

Author: claude

docker/Dockerfile

@@ -1,7 +1,8 @@
 # ObjectStack official runtime image — ghcr.io/objectstack-ai/objectstack
 #
-# A generic, app-agnostic production runtime: Node + @objectstack/cli +
-# `os start`. It contains NO app — bring your compiled artifact
+# A generic, app-agnostic production runtime: Node + @objectstack/cli + the
+# `pg` / `mysql2` SQL drivers + `os start`. It contains NO app — bring your
+# compiled artifact
 # (dist/objectstack.json, built by `os build` in CI):
 #
 #   FROM ghcr.io/objectstack-ai/objectstack:<version>

docker/README.md

@@ -1,9 +1,9 @@
 # ObjectStack Official Runtime Image
 
 `ghcr.io/objectstack-ai/objectstack` — the official production runtime for
-standalone ObjectStack apps. It packages Node 22 and `@objectstack/cli`
-(`os start`) and nothing else: **your compiled artifact is the app**, the
-image is the runtime.
+standalone ObjectStack apps. It packages Node 22, `@objectstack/cli`
+(`os start`) and the SQL drivers listed below — and no application code:
+**your compiled artifact is the app**, the image is the runtime.
 
 ```
 objectstack.config.ts ──(os build, CI)──▶ dist/objectstack.json ──(this image)──▶ running app