* Refactor module links and improve code documentation.
Updated documentation to rename "API" sections to "Code Link" for clarity and consistency. Enhanced docstrings for `circle_fitting` and `kmeans_clustering` functions, improving parameter descriptions and adding return value details. Fixed typos in function and file names in the ray casting grid map module.
* Fix import typo in ray casting grid map test module.
Corrected the import statement in the test file by updating the module's name to `ray_casting_grid_map` for consistency with the source file. This ensures proper functionality of the test suite.
