Added: examples covering all features

[sn]

This pull request significantly improves the README.md documentation for Nitro Image and adds a comprehensive set of example scripts demonstrating core library features. The documentation is now more detailed, organized, and user-friendly, while the new examples provide clear, practical usage for all major API capabilities.

Documentation improvements:

• Expanded the project description to clarify Nitro Image's core features, including its chainable, lazy-evaluated API and Pillow integration. Added a detailed feature list and reorganized the README into clear, themed sections.
• Updated and clarified usage examples throughout the README, including improved explanations and corrected or enhanced code snippets for resizing, cropping, overlays, responsive images, presets, batch processing, web framework integration, and configuration [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11].

New example scripts:

• Added eight example scripts (examples/01_basics.py through examples/08_placeholders.py) covering basics, resizing/cropping, transforms, adjustments/effects, format conversion, overlays, responsive sets, and placeholder generation. Each script is self-contained and demonstrates idiomatic usage of the API [1] [2] [3] [4] [5] [6] [7] [8].

Ecosystem and configuration updates:

• Updated the README's ecosystem section to better describe related Nitro projects and improved configuration documentation to reflect new or renamed options [1] [2].

These changes make the library much more accessible to new users and provide a robust reference for advanced features.