Add support for Renovate to detect and update Docker image versions
defined in Terraform files using annotation comments.
Changes:
- Add 3 regex managers to config.js.tpl for different annotation patterns:
- Basic: # renovate: datasource=docker
- With versioning: # renovate: datasource=docker versioning=semver
- Separate variable: # renovate: datasource=docker depName=redis
- Update README.md with comprehensive Docker container annotation docs
- Update QUICKSTART.md with Terraform Docker container examples
- Add example-annotated-containers.tf with usage patterns
This enables Renovate to automatically create PRs when Docker images
used in Terraform container definitions have updates available.
