docs: enhance hub contributing documentation with comprehensive guide… (#900)

* docs: enhance hub contributing documentation with comprehensive guidelines

- Add communication channels section (Discord, Discourse, GitHub)
- Expand testing section with accurate cscli hubtest workflow
- Add YAML best practices with real-world anchor examples
- Include AI-assisted generation guidelines with disclosure requirements
- Align PR checklist with enforced GitHub PR template
- Add troubleshooting section with common issues and solutions
- Consolidate redundant "Getting Started" and "Getting Involved" sections
- Fix MDX parsing issues and improve markdown formatting
- Add comprehensive git workflow and branch naming conventions
- Include detailed documentation requirements and examples

* fix: remove unnecessary backtick escaping in markdown

- Fix inline code backticks that were over-escaped
- Keep proper escaping only for backticks inside code blocks
- Improve markdown readability and rendering

* enhance: remove discussions

* fix: address colleague feedback on hub contributing docs

- Remove cscli hubtest coverage command that shows 0% and lacks filtering
- Remove ChatGPT remnants and unclear language
- Simplify PR checklist to avoid template duplication
- Remove vague performance troubleshooting item
- Remove redundant benefits section for cleaner flow

Author: LaurenceJJones