docs(gitbook): sync v4 docs from GitBook

[drichar]

Description

This PR integrates the v4 documentation from GitBook into the monorepo using GitBook's sync feature. The documentation is synchronized from GitBook (use-wallet docs) to the docs folder in the root of the monorepo.

Details

• Add initial v4 documentation files from GitBook sync
• Configure GitBook sync to commit changes to gitbook/v4 branch
• Place all documentation Markdown files in the docs folder
• Establish foundation for future documentation updates through GitBook sync
• Documentation covers v4.x features including:
  • Algorand SDK v3 support
  • Runtime node configuration
  • Custom networks support
  • Framework adapters (React, Vue, SolidJS)