Clarify auto-pause triggers on timeout expiry, not idle detection

Author: beran-t

docs/sandbox/persistence.mdx

@@ -227,7 +227,7 @@ sbx = Sandbox.connect(sandbox_id, timeout=60) # 60 seconds
 
 ### Auto-pause
 
-Sandboxes automatically pause when they've been idle, preserving their full state. You can resume at any time from exactly where you left off. The default inactivity period is 10 minutes — configure it with the `timeoutMs`/`timeout` parameter.
+Sandboxes automatically pause when their timeout expires, preserving their full state instead of shutting down. You can resume at any time from exactly where you left off. The default timeout is 10 minutes — configure it with the `timeoutMs`/`timeout` parameter.
 
 <CodeGroup>
 ```js JavaScript & TypeScript