docs: add password protection authentication documentation

fern/products/docs/docs.yml

@@ -299,6 +299,8 @@ navigation:
         path: ./pages/api-references/autopopulate-api-key.mdx
       - page: SSO
         path: ./pages/authentication/sso.mdx
+      - page: Password protection
+        path: ./pages/authentication/password.mdx
   - section: Security
     collapsed: true
     contents:

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

@@ -3,28 +3,29 @@ title: Overview of authentication options
 description: Understand the different authentication options Fern offers
 ---
 
-Fern offers two methods of authentication, Single Sign-On (SSO) and Role-Based Access Control (RBAC).
+Fern supports three ways to restrict access to your documentation:
 
-**For most situations, use RBAC** for granular access control over your documentation. RBAC works well for sites with multiple audiences (internal teams, partners, customers) and supports API key injection to autopopulate code examples.
-
-API key injection can be set up using either JWT or OAuth, depending on your existing authentication system.
-
-**SSO is simpler** but only provides basic login functionality - it doesn't support RBAC or API key injection. SSO works well for internal-only documentation where everyone should see the same content.
+- **RBAC** — Control which content different users can see. Supports [API key injection](/learn/docs/authentication/api-key-injection) via JWT or OAuth. Recommended for most use cases.
+- **SSO** — Require login without role management. Good for internal docs where all users see the same content.
+- **Password protection** — A single shared password for the entire site. Good for pre-release docs or basic access restriction.
 
 <Note>
 Learn how Fern handles user credentials and authentication in the [Security overview](/learn/docs/security/overview).
 </Note>
 
 Learn more about Fern's authentication options:
 
-<CardGroup cols={3}>
-  <Card title="Role-based access control" icon="fa-duotone fa-people-group" href="/docs/authentication/rbac">
+<CardGroup cols={2}>
+  <Card title="Role-based access control" icon="fa-duotone fa-people-group" href="/learn/docs/authentication/rbac">
     Granular access for different audiences
   </Card>
-  <Card title="API Key Injection" icon="fa-duotone fa-key" href="/docs/authentication/api-key-injection">
+  <Card title="API key injection" icon="fa-duotone fa-key" href="/learn/docs/authentication/api-key-injection">
     JWT or OAuth flows available
   </Card>
-  <Card title="SSO" icon="fa-duotone fa-user-check" href="/docs/authentication/sso">
+  <Card title="SSO" icon="fa-duotone fa-user-check" href="/learn/docs/authentication/sso">
     Basic functionality and simple setup
   </Card>
-</CardGroup>
+  <Card title="Password protection" icon="fa-duotone fa-lock" href="/learn/docs/authentication/password-protection">
+    Shared password for simple access control
+  </Card>
+</CardGroup>

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

@@ -0,0 +1,16 @@
+---
+title: Password protection
+subtitle: Protect your documentation site with a shared password for simple access control.
+---
+
+<Markdown src="/snippets/enterprise-plan.mdx"/>
+
+Password protection allows you to restrict access to your documentation site using a shared password. This is useful for pre-release documentation, internal resources, or any content you want to keep private without requiring individual user accounts.
+
+## How it works
+
+When password protection is enabled, visitors to your documentation site are prompted to enter a password before they can view any content. Once authenticated, users can browse the site until their session expires.
+
+## Setting up password protection
+
+To enable password protection for your documentation site, [contact Fern](https://buildwithfern.com/contact) or reach out via Slack. Fern will configure the password for your site.