Improve comments, add doctests to coloring.py

[Hardvan]

Added more comprehensive comments and more doctests to each function present in coloring.py.

• [ ] Add an algorithm?
• [ ] Fix a bug or typo in an existing algorithm?
• [x] Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• [x] Documentation change?

Checklist:

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized.
• [x] I know that pull requests will not be merged if they fail the automated tests.
• [x] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [x] All new Python files are placed inside an existing directory.
• [x] All filenames are in all lowercase characters with no spaces or dashes.
• [x] All functions and variable names follow Python naming conventions.
• [x] All function parameters and return values are annotated with Python type hints.
• [x] All functions have doctests that pass the automated testing.
• [x] All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• [x] If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[Hardvan]

Keep comments short to not slow down the reader.

The ruff rules D can be quite useful.

I have committed the suggested comment changes and marked the changes as resolved.

[cclauss]

Please remove the duplicate type hints in comments so the following command passes without errors. % ruff check --select=D417 backtracking/coloring.py

[Hardvan]

Please remove the duplicate type hints in comments so the following command passes without errors. % ruff check --select=D417 backtracking/coloring.py

I'm sorry for missing this! I have removed the argument type hints in the function docstring.