refactor: Enhance docs, add more tests in WelshPowell

[Hardvan]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.69%. Comparing base (a78b15d) to head (4c6fefd).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5971      +/-   ##
============================================
+ Coverage     71.68%   71.69%   +0.01%     
  Complexity     4946     4946              
============================================
  Files           650      650              
  Lines         17565    17565              
  Branches       3384     3384              
============================================
+ Hits          12592    12594       +2     
+ Misses         4499     4498       -1     
+ Partials        474      473       -1     

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