Fix grammar issues throughout the repository's markdown files:
- Correct spelling errors (e.g., defination → definition, intepreter → interpreter)
- Fix capitalization at sentence starts
- Correct article usage and verb agreement
- Fix run-on sentences with proper punctuation
- Standardize technical terms (e.g., posix → POSIX, python → Python)
- Fix possessive vs contraction errors (it's → its)

Addresses issue #59

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>