Fix typos and grammar in CONTRIBUTING.md

[Scarmonit]

Fixed several typos and grammar issues:

• Changed "mantained" to "maintained"
• Changed "situaitions" to "situations"
• Changed "retrospectivly" to "retrospectively"
• Changed "maintainers" to "maintainer's" for proper possessive
• Changed "airing" to "erring" (in context of "erring on the side of caution")

These corrections improve readability and professionalism of the documentation.

GitHub Issue: N/A - Minor documentation fixes

Summary: This PR corrects spelling and grammar errors in the CONTRIBUTING.md file to improve clarity and professionalism.

Do you think resolving this issue might require an Architectural Decision Record (ADR)? (significant or noteworthy)

No - These are minor typo and grammar corrections that do not constitute a significant or noteworthy change to project architecture or decision-making processes.