[Confidential Ledger] [DP] Update Readme and sample related to tags

[musabbir]

Description

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
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[Copilot]

Pull Request Overview

This PR adds a new sample script demonstrating how to write and query ledger entries using tags, and updates the README to document tags support and usage examples.

• Introduces use_tags.py sample illustrating tag-based grouping and retrieval of entries.
• Expands README with a Tags section and code snippets for writing and listing entries by tag.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
sdk/confidentialledger/azure-confidentialledger/samples/use_tags.py	New sample for creating and querying ledger entries with tags.
sdk/confidentialledger/azure-confidentialledger/README.md	Documentation added for tags support, including usage and examples.