docs: Add network volume permissions to roles and permissions table (#452)

Author: muhsinking

get-started/manage-accounts.mdx

@@ -63,6 +63,7 @@ Runpod provides four distinct roles to control access within team accounts. Each
 | Send requests to Serverless endpoints | ✅ | ❌ | ✅ | ✅ |
 | Connect to existing Instant Clusters | ✅ | ❌ | ✅ | ✅ |
 | Create/delete/start/stop Instant Clusters | ❌ | ❌ | ❌ | ✅ |
+| Create/update/delete network volumes | ❌ | ❌ | ✅ | ✅ |
 | View billing information | ❌ | ✅ | ❌ | ✅ |
 | Manage payment methods | ❌ | ✅ | ❌ | ✅ |
 | Invite team members | ❌ | ❌ | ❌ | ✅ |