Update README with complete documentation

[mmucklo]

• Add LengthLimits configuration section with examples
• Document comment extraction feature with examples
• Update ParseOptions constructor signature
• Add comments field to all return value examples
• Include simple_address and other missing fields
• Document default RFC length limits
• Add examples for createDefault() and createRelaxed() factory methods
• Make README comprehensive yet easy to understand

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.02%. Comparing base (c479cc4) to head (7b0d41e).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master      #48   +/-   ##
=========================================
  Coverage     77.02%   77.02%           
  Complexity      219      219           
=========================================
  Files             3        3           
  Lines           505      505           
=========================================
  Hits            389      389           
  Misses          116      116           

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