**Summary**
- Update the quantization document that default qconfig with oneDNN backend is recommended to be used on CPUs with Vector Neural Network Instruction support.
- Add the warning message when user uses default qconfig with oneDNN backend on CPU without Vector Neural Network Instruction support.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103653
Approved by: https://github.com/jgong5, https://github.com/malfet