Container tag in the data.yaml file is deprecated

[josill]

Description

The Quick Start documentation uses the deprecated YAML key format (container.tag) instead of the JSONPath format ($.container.tag). This causes Updatecli to emit warnings during the demo, creating confusion for users following the guide.

Steps to reproduce

1. Follow the Quick Start guide at /docs/prologue/quick-start/
2. Run updatecli diff --config manifest.yaml using the example manifest
3. Observe the warning: WARNING: current yaml key is "container.tag" and should be updated to "$.container.tag"

Files affected:

• assets/code_example/docs/prologue/quickstart/updatecli.yaml
• content/en/docs/prologue/quick-start.adoc

Expected result

The demo should run without warnings. The documentation and example manifest should use the correct JSONPath format ($.container.tag).

Actual result

Updatecli emits deprecation warnings during the demo, which confuses users who are following the Quick Start guide.

Environment

• OS: macOS 24.6.0 (Darwin)
• Updatecli version: 0.113.0