Docs: Comprehensive project documentation update

[JacobBorden]

This commit includes extensive updates to the project's documentation:

1. README.md:

   • I verified and updated the "Features" section to accurately reflect current library capabilities, distinguishing between the old API and the new BmpTool API.
   • I clarified "Dependencies" and "Core Modules" sections.
   • I improved the BmpTool API explanation and replaced the example with a more comprehensive one from main.cpp, demonstrating a full load-process-save cycle.
   • I updated "Building the Project" with more detailed instructions and clarified test execution.
   • I added a "Code Documentation" section explaining Doxygen usage for include/bitmap.hpp and providing instructions for local documentation generation.
   • I added a "Contributing" section with basic guidelines.

2. src/matrix/Documentation/Matrix.MD:

   • I performed a thorough review and update to align with src/matrix/matrix.h.
   • I corrected descriptions for iterator template parameters, operator behaviors, and const-correctness.
   • I documented previously undocumented constructors, destructors, assignment operators, and member functions for MatrixRow<T> and Matrix<T>.
   • I updated function signatures, return types (e.g., for in-place methods and compound assignment operators), and parameter types to match the current implementation.
   • I clarified differences between at() (bounds-checked) and operator[] (no bounds-checking).
   • I revised the "Potential Improvements" section to reflect implemented features and add new suggestions.
   • I updated usage examples.

3. CHANGELOG.md:

   • I added entries under version 0.3.0 to record the significant updates made to README.md and src/matrix/Documentation/Matrix.MD.

These changes ensure that the project documentation is current, accurate, and provides comprehensive guidance for you and contributors.