Add comprehensive coding patterns documentation for software engineering

[Copilot]

This PR adds a comprehensive guide to coding patterns in software engineering to address the learning objective in the Dev-Journal repository.

What's Added

New Documentation: coding-patterns-in-software-engineering.md

• Complete coverage of the three main categories of design patterns:
  • Creational Patterns: Singleton, Factory Method, Builder, Abstract Factory, Prototype
  • Structural Patterns: Adapter, Decorator, Facade, Composite, Proxy
  • Behavioral Patterns: Observer, Strategy, Command, State, Template Method, Chain of Responsibility, Visitor, Mediator

Key Features:

• Practical code examples in Python for each pattern
• Clear explanations of purpose, use cases, pros and cons
• Architectural patterns section covering MVC, MVVM, Repository pattern, Dependency Injection
• Best practices and guidelines for when and how to use patterns
• Common pitfalls and implementation guidelines

Repository Structure:

• Updated README.md to include a "Topics Covered" section that references the new documentation
• Maintains the repository's purpose as a personal learning journal

The documentation serves as a comprehensive reference for understanding and implementing design patterns, making it a valuable addition to this learning-focused repository.

Fixes #26.

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