Suggestion: Improve code snippet readability in documentation for easier copy-paste #509

Hi,

I wanted to suggest an improvement to the documentation format gently. While the .. testcode:: blocks are great for testing examples, they present two minor friction points for new users:

1. Readability
   The indented code blocks without syntax highlighting make it harder to scan/understand examples quickly

2. Copy-Paste Experience
   When copying code directly from GitHub's rendered documentation:

   • The extra indentation requires manual adjustment
   • Hidden .. testoutput:: blocks can accidentally get copied

Would you consider either:

• Adding triple-backtick (```python) code fences alongside testcode blocks
• Including a "Copy to Clipboard" button via Sphinx extensions (like this one)
• Adjusting indentation levels for better copy-paste ability

This would make it even easier for folks to:

1. Quickly try examples from the docs
2. Experiment with Tenacity's awesome features
3. Adopt best practices faster

I'm happy to help submit a PR if this aligns with the project's direction! Just let me know what approach you'd prefer.

Thanks!