Improve Logger Middleware Documentation

[lscannon12]

This pull request enhances the documentation for Echo's Logger middleware. The improvements aim to provide clearer, more comprehensive information for users implementing logging in their Echo applications.

Key changes include:

• Expanded overview of the Logger middleware and its features
• More detailed configuration options with examples
• Advanced usage scenarios, including custom output and route-specific logging
• Best practices for using the Logger middleware effectively
• Performance considerations for high-traffic scenarios

These updates should help both new and experienced Echo users better understand and utilize the Logger middleware, leading to improved debugging and monitoring capabilities in their applications.