Add SSO docs (#141)

Author: dannysheridan

fern/products/docs/pages/authentication/sso.mdx

@@ -1,7 +1,30 @@
 ---
 title: Single Sign-On
+subtitle: Enterprise authentication for secure access to your Fern dashboard
 ---
 
-Fern supports SSO so that your docs site is gated for your team and customers.
+Fern’s Single Sign-On (SSO) is an enterprise feature that lets your team securely access the Fern dashboard at `dashboard.buildwithfern.com` using your organization’s identity provider. This is designed for internal contributors, such as technical writers, product managers, or engineers, who need access to want to contribute to your documentation, view web analytics, or manage organizational settings.
 
-<Warning>Docs are coming soon for this page.<br/><br/>Please [book a demo](https://buildwithfern.com/book-demo) or [reach out to us](https://buildwithfern.com/book-demo) to get set up with this feature. </Warning> 
+## What SSO unlocks
+
+When SSO is enabled for your organization, authenticated users of Fern gain access to:
+
+- **Manage Users of your Organization**: Add teammates and configure settings for your organization
+- **Access Ask Fern Analytics**: See AI-assisted search usage and browse verbatim user questions
+- **View Web Analytics**: Track key site metrics, like page views and unique visitors **(coming soon)**
+- **Use the Visual Editor**: Make edits to your docs from the browser
+
+## How it works
+
+Fern's SSO integration allows your team to use their existing corporate credentials to access the Fern dashboard. Instead of managing separate Fern accounts, users authenticate through your organization's identity provider and are automatically granted appropriate access to your Fern resources.
+
+## Supported identity providers
+
+Fern supports SSO integration with any identity provider that implements industry-standard protocols:
+
+- **SAML 2.0**: Compatible with providers like Okta, OneLogin, Azure AD, and others
+- **OIDC (OpenID Connect)**: Works with Google Workspace, Auth0, and other OIDC-compliant providers
+
+<Note>
+SSO is available as part of the Enterprise plan. Reach out via Slack or [contact our team](https://buildwithfern.com/contact) to begin the SSO setup process.
+</Note>