Implement Shells.com OS Creation Tutorial with automated template generation system

[Copilot]

This PR implements a comprehensive tutorial and template generation system for Shells.com OS creation as requested in the issue. The implementation provides both documentation and automation to maintain up-to-date configuration templates.

📖 Tutorial Documentation

Added docs/shells-os-creation-tutorial.md with detailed guidance covering:

• Creating Shells images from existing Shell™ instances via the console
• Migrating from Virtual Machines using qemu-img and rbdconv tools
• Running custom kernels with proper BIOS/UEFI and disk resize capabilities
• Integration with existing documentation and build systems

📁 Template System

Created an organized template structure in templates/ with:

• 31 configuration templates across 5 distributions (debian, fedora, manjaro, opensuse, ubuntu)
• Distribution-organized directories for easy navigation
• Comprehensive template content including build commands, requirements, testing instructions, and cross-references
• Automatic desktop vs server detection with appropriate feature descriptions

Example template structure:

templates/
├── debian/
│   ├── debian-bullseye-gnome-desktop.md
│   └── debian-bullseye-ssh-server.md
├── ubuntu/
│   ├── ubuntu-focal-ubuntu-desktop.md
│   └── ubuntu-jammy-openssh-server.md
└── README.md

🔧 Automation Infrastructure

Template Generation Script (generate_templates.sh)

• Parses official_images.txt to generate templates for all supported configurations
• Automatically detects distribution, version, and variant information
• Creates appropriate directory structure and template content
• Handles both desktop and server configuration types

GitHub Action (.github/workflows/generate-templates.yml)

• Triggers: Changes to official_images.txt, manual dispatch, weekly schedule
• Functionality: Automatically regenerates templates when configurations change
• Output: Commits updated templates with detailed change descriptions
• Summary: Provides build summaries with configuration counts and distribution breakdown

📚 Documentation Integration

Updated README.md to include:

• Reference to the new OS Creation Tutorial
• Links to the template system
• Clear navigation between related documentation

All templates include cross-references to:

• Related configuration scripts (oscfg/*.sh)
• Build and testing instructions
• OS requirements documentation
• The main tutorial

✅ Verification

The implementation has been thoroughly tested:

• All 31 templates generated correctly match configurations in official_images.txt
• Template structure includes all required sections (build commands, requirements, testing, references)
• Script handles new configuration additions dynamically
• GitHub Action workflow syntax validated
• Documentation cross-references verified

This provides a scalable, automated system that will maintain current documentation as new OS configurations are added to the repository.

Fixes #1.

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[drzo]

excellent