chore: add Disclaimer for docker-based templates

[phorcys420]

This PR adds a production disclaimer to docker-build and updates the permission instructions for other Docker-based templates.

[Copilot]

Pull Request Overview

This PR adds documentation improvements for Docker-based Coder templates, focusing on production usage guidance and installation scenarios. The changes provide clearer setup instructions for different deployment methods.

• Adds production usage disclaimer for the docker-build template
• Updates README files to distinguish between Docker-containerized and system package Coder installations
• Standardizes Docker setup instructions across multiple template READMEs

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
registry/coder/templates/docker/README.md	Restructures infrastructure section to cover both Docker and system installations
registry/coder/templates/docker-devcontainer/README.md	Adds Docker installation guidance and updates command syntax
registry/coder-labs/templates/docker-build/README.md	Adds production disclaimer and comprehensive Docker setup instructions

[matifali]

Looks Good, but can we also link our existing docs on how to use an external Docker host?
https://coder.com/docs/admin/templates/extending-templates/provider-authentication#use-a-remote-docker-host-for-authentication

[phorcys420]

@matifali I think we link only to https://registry.terraform.io/providers/kreuzwerker/docker/latest/docs#remote-hosts because that page you sent talks about external provisioners and i think will only cause confusion

[DevelopmentCats]

@phorcys420 you might need to 'bun run fmt' to format so the CI will pass.