Update API Specifications for Group 2 Onboarding

There have been recent discussions in Discourse raising concerns that our published API specifications may be outdated or inaccurate. Additionally, some recent feature changes might not yet be reflected in the current API documentation.

**Problem:**
• API specs used during onboarding may contain inaccuracies or missing details.
• This creates confusion for new API users and increases support overhead.
• Any recent feature updates or parameter changes may not be properly documented.

**Goal:**

To ensure API users receive accurate, complete, and up-to-date specifications during onboarding, reducing confusion and support requests.

**Tasks :**

- [ ] Review the current API specifications required for Group 2 onboarding. Focus on the features and filings that will be available for this particular group (the filings currently available in Production are the priority).
- [ ] Compare them against the live API behavior and recent feature updates.
- [ ] Identify and correct any inconsistencies, outdated information, or missing fields.
- [ ] Coordinate with the dev team to confirm recent or upcoming changes that might impact the specs.
- [ ] Review feedback from Discourse threads.
- [ ] Update the specs and publish a revised version.

Please add sub-tickets as needed.