Docs: add documentation about best practices

[leandrodamascena]

Create documentation for best practices when working with durable functions, covering function design, timeout configuration, naming conventions, performance optimization, and common mistakes to avoid.

Solution

Create best practices docs for tests with:

• Function design - Best practices for structuring durable functions
• Timeout configuration - Recommendations for setting appropriate timeouts
• Naming conventions - Guidelines for naming operations consistently
• Performance optimization - Tips for improving execution performance
• Common mistakes - Warnings about pitfalls to avoid
• Code organization - Patterns for organizing durable function code
• FAQ - Common questions about best practices