CEXT-6400: admin-ui-sdk v2 samples

[obarcelonap]

Description

Update admin-ui-sdk/README.md to document the v1/v2 directory structure and provide a side-by-side sample comparison table showing what changed between versions.

Related Issue

CEXT-6400

Motivation and Context

The admin-ui-sdk directory now contains both v1/ and v2/ sample sets. Without updated docs, it's unclear which version to use or how V1 samples map to their V2 equivalents. This README update makes the versioning explicit and helps developers migrate from V1 to V2.

How Has This Been Tested?

Documentation-only change — verified by reviewing the rendered Markdown.

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.