Expand Ask Fern authentication and RBAC documentation

[devin-ai-integration]

Expand Ask Fern RBAC documentation with authentication details

Summary

Expands the Ask Fern RBAC documentation page from a brief 2-paragraph overview to a comprehensive guide covering authentication flow and role-based filtering. This feature was implemented in fern-platform PR #5431 but was not documented in the user-facing docs.

The expanded documentation explains:

• How Ask Fern authenticates users via FERN_TOKEN
• The verification flow against the documentation's auth endpoint
• How role-based filtering works at the search level
• Multi-role requirements and fallback behavior

Review & Testing Checklist for Human

• Verify authentication flow accuracy: Confirm the 4-step authentication process matches actual Ask Fern behavior, especially the FERN_TOKEN header and verification endpoint details
• Validate terminology: Check if "FERN_TOKEN" is the correct user-facing term or if there's a more abstract way to describe the authentication mechanism
• Test multi-role syntax: Verify the example "admin&developer" accurately represents how multi-role requirements are expressed in the system
• Review filtering explanation: Confirm "version and product filtering" is accurate and sufficiently clear, or if it needs more detail about how these filters work
• Check completeness: Ensure the documentation provides enough context for users setting up Ask Fern with RBAC (may need links to setup instructions or prerequisites)

Test Plan

1. Navigate to /learn/ask-fern/rbac in the documentation
2. Read through the expanded content as if you're a user setting up Ask Fern with RBAC
3. Verify all technical details match the actual implementation in fern-platform
4. Check if any important details are missing or if anything is confusing

Notes

• Based on code review of fern-platform PR #5431 (auth verification and role-based filtering)
• I documented the authentication flow from reading the Python implementation but haven't tested it hands-on, so technical accuracy review is critical
• The "version and product filtering" mention might be too vague - consider if this needs expansion or removal
• Session: https://app.devin.ai/sessions/ef0744e80a96482a85c0f5cec53e4b4b
• Requested by: [email protected] (@dannysheridan)
• Assignee: @tsbhangu (author of fern-platform PR #5431)

[devin-ai-integration]

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