Document Ask Fern RBAC feature (#706)

Author: devalog

fern/products/ask-fern/pages/features/rbac.mdx

@@ -0,0 +1,8 @@
+---
+title: Role-based access control for Ask Fern
+description: Ask Fern respects your documentation's role-based access control settings.
+---
+
+Ask Fern automatically respects the [role-based access control (RBAC) settings configured in your documentation](/docs/authentication/rbac). When users query Ask Fern, they only receive answers from documentation they have permission to access based on their assigned roles.
+
+This works at all levels, from entire sections down to individual pages and conditional content within pages. 

fern/products/ask-fern/pages/getting-started/how-it-works.mdx

@@ -27,7 +27,7 @@ The main parts of the Ask Fern system are:
   models. They're stored in a database that serves as Ask Fern's search index. 
 * **Query processing** – When users ask questions, Ask Fern vectorizes their
   query and searches the database to find the most relevant documentation and
-  code chunks.
+  code chunks. If you have [role-based access control](/docs/authentication/rbac) configured, Ask Fern filters results based on the user's permissions.
 * **Response generation** – Ask Fern uses the retrieved chunks as context to
   generate accurate answers with [citations](/ask-fern/features/citations) for the user. If the initial context isn't sufficient, it performs an additional keyword search. 
 
@@ -45,11 +45,12 @@ sequenceDiagram
     
     U->>C: Submit question via Ask Fern searchbox
     C->>C: Convert query to vector
+    C->>C: Check user roles (if RBAC enabled)
     C->>V: Search for relevant chunks
-    V->>C: Return matching documents
+    V->>C: Return matching documents user can access
     C->>A: Send query + context
     A->>V: Perform additional keyword search if needed
-    V->>A: Return additional chunks
+    V->>A: Return additional chunks user can access
     A->>A: Generate response
     A->>U: Return answer with citations
 ```

fern/products/ask-fern/pages/getting-started/what-is-ask-fern.mdx

@@ -62,4 +62,12 @@ Ask Fern helps you:
     Add custom documents to Ask Fern. 
   </Card>
 
+  <Card 
+    title="Role-based access control" 
+    icon="regular shield-alt"
+    href="/learn/ask-fern/configuration/documents" 
+    >
+    Ask Fern enforces your documentation's role-based permissions.
+  </Card>
+
 </CardGroup>