Add Cron Pattern guide with syntax breakdown and examples

[dhruv-dabhi-st7]

• Purpose To improve developer understanding of cron expressions in Deno by providing detailed documentation about each asterisk position and common patterns.

• The current documentation shows basic cron usage but lacks detailed explanation of the cron syntax pattern * * * * * and what each position represents.

Suggested Improvements

1. Add a clear breakdown of the cron syntax:

// Cron syntax: * * * * *
//              │ │ │ │ │
//              │ │ │ │ └── Day of week (0-6 or SUN-SAT)
//              │ │ │ └──── Month (1-12)
//              │ │ └────── Day of month (1-31)
//              │ └──────── Hour (0-23)
//              └────────── Minute (0-59)

Benefits

• Reduces confusion for developers new to cron syntax
• Provides quick reference for common scheduling patterns
• Improves developer productivity with clear examples

Additional Context

This enhancement aligns with Deno's goal of providing clear, comprehensive documentation for its features.