Feature - Add code readability docs, main README info and TOCs to all docs

[goodslav]

• Adds code readability docs;
• Adds main README file info with a Table of Contents (TOC) with links to all the individual guideline pages;
• Adds TOCs to all guideline docs with multiple and nested headings (I know GitHub automatically adds a dropdown with TOC links to all headings if the .md page has multiple headings but a lot of people don't know about this feature and where to find it and I think we will need TOC menus on all the pages as we also plan to export them as PDF files with a GitHub action in the future).