docs: Add comprehensive Jupyter Notebooks documentation

[int-arsh]

Description

Closes #4967

This PR consolidates scattered Jupyter Notebook documentation into a comprehensive, dedicated page at docs/usage_and_configuration/jupyter_notebooks.md.

Problem: Currently, Jupyter-related information is scattered across multiple documentation files (README.md, getting_started.md, FAQ, source_version_control.md), making it difficult for users to find complete information about using Black with Jupyter Notebooks.

Solution: Created a single authoritative page that covers:

• Installation with pip install "black[jupyter]"
• Basic usage and command-line examples
• How Black formats notebooks (what's preserved, what's changed)
• Cells that won't be formatted (automagics, cell magics, etc.)
• Configuration options (--python-cell-magics, --skip-magic-trailing-comma)
• Pre-commit integration with black-jupyter hook
• Editor integration references
• Troubleshooting common issues

Testing: Documentation builds successfully with strict mode:

sphinx-build -a -b html -W docs/ docs/_build/

Checklist - did you ...

• Implement any code style changes under the --preview style, following the stability policy?
  • N/A - This is a documentation-only change
• Add an entry in CHANGES.md if necessary?
  • N/A - Documentation changes don't require changelog entries
• Add / update tests if necessary?
  • N/A - Documentation verified via sphinx-build -W
• Add new / update outdated documentation?
  • Yes - Created comprehensive Jupyter documentation page

[int-arsh]

@cobaltt7
This is a documentation-only change, so a changelog entry isn’t required.