refactor: Enhance docs, add tests in RotateSinglyLinkedLists

[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 70.13%. Comparing base (e1a0155) to head (0f2ad4f).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6011      +/-   ##
============================================
+ Coverage     70.12%   70.13%   +0.01%     
- Complexity     4748     4750       +2     
============================================
  Files           633      633              
  Lines         17279    17279              
  Branches       3326     3326              
============================================
+ Hits          12117    12119       +2     
  Misses         4704     4704              
+ Partials        458      456       -2     

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