Add required packages table to README Installation section

[Copilot]

Added a comprehensive table documenting all required packages and their purposes to improve user understanding of dependencies.

Changes Made

• Added Required Packages table in the Installation section with three columns:
  • Package: Lists all 10 packages from requirements.txt
  • Purpose: Brief description of each package's functionality
  • Usage in Application: Specific explanation of how each package is used in the Streamlit Search App

Package Documentation

The table includes detailed information for:

• UI Components: streamlit, streamlit-chat, streamlit-option-menu for web interface
• AI/LLM Integration: openai, langchain for Azure OpenAI and document processing
• Search & NLP: faiss-cpu, transformers for vector similarity search and tokenization
• Data Processing: pandas, numpy for data manipulation and numerical operations
• HTTP Communication: requests for API calls to Azure services

Benefits

• Users can now understand why each dependency is needed before installation
• Clearer context for troubleshooting package-related issues
• Better onboarding experience for new developers
• Maintains existing installation instructions while adding helpful context

The table is strategically placed before the existing pip install commands to provide context without disrupting the current workflow.

Fixes #8.

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