Feature doc explane quant algorithms 2

[KazunoriSumiya]

Pull Request Description:

・Added description of quantization (per-tensol/per-channel) to FAQ
・Added explanation to QuantizationErrorMethod documentation

The following four sources were modified, and the others were generated.
・FAQ.md
・docsrc/source_troubleshoot/troubleshoots/threhold_selection_error_method.rst
・model_compression_toolkit/core/common/quantization/quantization_config.py
・quantization_troubleshooting.md

Checklist before requesting a review:

• I set the appropriate labels on the pull request.
• I have added/updated the release note draft (if necessary).
• I have updated the documentation to reflect my changes (if necessary).
• All function and files are well documented.
• All function and classes have type hints.
• There is a licenses in all file.
• The function and variable names are informative.
• I have checked for code duplications.
• I have added new unittest (if necessary).