Improve samples, .env based for secrets for embedding skills notebook

[Ellerbach]

Description

Improve samples, .env based for secrets for embedding skills notebook

Type of Change

• 🐛 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 not work as expected)
• 📝 Documentation update
• 🔧 Configuration change
• ♻️ Refactoring (no functional changes)

Related Issue

Azure AI Search Reference

Checklist

Code Quality

• My code follows the coding standards of this project
• I have used meaningful names for variables, methods, and classes
• I have kept methods small and focused (single responsibility)
• I have used async/await for I/O operations where appropriate

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have run dotnet test and all tests pass

Documentation

• I have updated the documentation as needed
• I have added XML documentation for new public APIs
• I have updated the CHANGELOG.md if applicable

General

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes