Update doc GUIDELINES to add English Spell Checking section

[yada]

This update explains how Microcks uses automated English spell checking via GitHub Actions.
It provides contributors with:

• A quick overview of the misspell tool used for validation
• Step-by-step instructions to run spell checks locally
• Examples of output and how to handle false positives by updating .wordlist.txt

This helps maintain high-quality documentation and speeds up the contribution process. Let’s keep the docs clean and typo-free! 🚀