Add team members by plan section to permissions page

[devin-ai-integration]

Summary

Adds a new "Team members by plan" section to the permissions page that documents the number of team members included with each pricing plan (Hobby: 2, Pro: 5, Enterprise: Custom). The section is placed above the existing "Role types" section and links to the pricing page for reference.

Review & Testing Checklist for Human

• Verify member counts are accurate: Confirm that Hobby = 2, Pro = 5, and Enterprise = Custom match what's currently on buildwithfern.com/pricing. These were read visually from the pricing page.
• Check if any plans are missing: Verify there isn't a Free tier or other plan that should also be listed in the table.
• Confirm placement feels right editorially: The new section sits between the intro paragraph and "Role types" — confirm this is the best location for discoverability.

Notes

• Link to Devin run
• Requested by: Fern Support

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-24c9a813-d257-4dbc-84f3-26c77394a4f4.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/dashboard/configuration/permissions