[fix/docs]: Code improvements in Fibbonacci algorithm. Code is documented.

[sudonims]

Description of Change

Checklist

• Added description of change
• Added documentation so that the program is self-explanatory and educational - Doxygen guidelines
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• I acknowledge that all my contributions will be made under the project's license.

Notes:

[kvedala]

Thank you @sudonims
But this code seems like a duplicate of two other files in the math folder: math/fibonacci.cpp and math/fibonacci_fast.cpp
You may contribute by deleting this additional file by updating this same pull-request without creating a new one.

[sudonims]

Thank you @sudonims
But this code seems like a duplicate of two other files in the math folder: math/fibonacci.cpp and math/fibonacci_fast.cpp
You may contribute by deleting this additional file by updating this same pull-request without creating a new one.

Ohh...didn't see that. Deleted the file.

[kvedala]

Thank you 👍