docs: document custom domain TXT verification records

[mintlify]

Summary

Document the _acme-challenge and _cf-custom-hostname TXT records that the dashboard now displays and automatically verifies when you add a custom domain.

Changes

• Added a "Verification TXT records" section under "Configure your DNS" explaining the two TXT records, what they're for, and that the dashboard auto-checks their status.
• Updated TLS provisioning copy to reference Mintlify's automatic certificate flow instead of Vercel.
• Removed the outdated "Vercel verification" accordion.

Context

The upstream change adds automatic verification of custom-domain TXT records via DNS lookups, and surfaces the records and their configuration status in the dashboard. The existing custom domain page didn't mention these records, so users following the dashboard prompts had no documentation explaining what to add or why.

---

Note

Low Risk
Low risk documentation-only change; main risk is minor user confusion if DNS record examples or sequencing guidance is inaccurate.

Overview
Updates the custom domain guide to document the two required verification TXT records (including what they do and that the dashboard auto-verifies them) before TLS provisioning can complete.

Clarifies cutover sequencing to wait for TXT verification before changing the CNAME to avoid temporary HTTPS failures, and removes the outdated provider-specific Vercel verification accordion while keeping Cloudflare guidance.

^{Reviewed by Cursor Bugbot for commit d391349. Bugbot is set up for automated code reviews on this repo. Configure here.}

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated (UTC)
mintlify	🟢 Ready	View Preview	May 6, 2026, 6:44 AM

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 800d62f. Configure here.}