docs: Add GPU memory requirements table (Fixes #167)

[pratik26x]

Description

Adds detailed GPU memory requirements table to README.md to help users select appropriate hardware configurations (Addresses Issue #167).

Changes

• Added comprehensive VRAM specifications for:
  • Gemma 2B, 7B, and 12B model variants
  • Both bf16 and int4 quantizations
• Included:
  • Minimum required VRAM
  • Recommended VRAM for optimal performance
  • Notes about framework overhead

Impact

• Helps users avoid OOM errors by selecting compatible hardware
• Provides clear guidance for different model sizes and precisions
• Complements existing system requirements documentation

Fixes #167

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[pratik26x]

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[pratik26x]

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