[Documentation] QAT to PTQ migration

[daniil-lyakhov]

My view on NNCF documentation:

• Algorithms:
  • Quantization
    • PTQ
    • QAT ( nncf.quantize (with note: you can quantize TF models and use additional algorithms (HAWQ), please refer to additional algorithm section.)
  • Other Algorithms
    • Advanced quantization (HAWQ, AA, etc)
      • Pruning
      • Sparisty
      • Quantization (legacy)

Changes

• Usage is updated

Reason for changes

• To align documentation with the latest changes in torch QAT

Related tickets

129586