Add PySpring Scheduler Documentation

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Add PySpring Scheduler Documentation

Description

This PR adds comprehensive documentation for the PySpring Scheduler feature, which provides a robust and flexible way to manage scheduled tasks in PySpring applications. The documentation covers installation, configuration, usage patterns, and best practices.

Changes

• Added new documentation file docs/guide/scheduling/scheduler.md
• Updated mkdocs.yml to include the new scheduler documentation in the navigation

Documentation Coverage

The new documentation includes:

• Installation instructions
• Overview of the scheduler's capabilities
• Configuration options and setup
• Usage examples with different trigger types (Interval, Cron)
• Component-based scheduling with dependency injection
• Best practices for resource management and error handling
• Common use cases and troubleshooting guide

Testing

• Documentation builds successfully with MkDocs
• All code examples are properly formatted
• Navigation structure is correct

Related Issues

[Add any related issue numbers here]

Additional Notes

The scheduler documentation is based on the current implementation of the PySpring Scheduler package, which is built on top of APScheduler and integrates with PySpring's dependency injection system.