Document Proposal Discussion Forum Moderation Process in GitBook

## Description
Create a **GitBook documentation** explaining how moderation works for the **Proposal Discussion Forum** to ensure healthy, constructive, and inclusive discussions. The documentation should cover the moderation system, user interactions, escalation processes, and security measures.

## Acceptance Criteria
- [ ] A **GitBook page** is created detailing the moderation process.
- [ ] Documentation explains **how users can flag comments** and includes a step-by-step guide.
- [ ] The **escalation process** is clearly defined, including thresholds and reviewer actions.
- [ ] The **role of the GovTool Working Group** in moderation decisions is outlined.
- [ ] Security measures, including **hashing for moderation actions**, are documented.
- [ ] All information is **structured and easy to understand** for both users and moderators.