Add CMake Basics and Usage Documentation

[mrshaw01]

Introduce a section explaining CMake for building C++ projects. This will help beginners understand project setup and build configuration.

Actions:

• Create a new folder: cmake/ or cpp/cmake/

• Add docs covering:

  • Basic CMakeLists.txt structure
  • Common commands and variables
  • Example project with build instructions

• Optionally include tips for integrating with IDEs or Pybind11

Clear CMake documentation will make this repo more beginner-friendly and complete for C++ developers.