Update pdf-endpoint.mdx

fix nesting

Author: kathayl

src/content/docs/browser-rendering/rest-api/pdf-endpoint.mdx

@@ -120,7 +120,7 @@ curl -X POST 'https://api.cloudflare.com/client/v4/accounts/<accountId>/browser-
   --output "advanced-output.pdf"
 ```
 
-## Blocking images and styles when generating a PDF
+### Blocking images and styles when generating a PDF
 
 The options `rejectResourceTypes` and `rejectRequestPattern` can be used to block requests during rendering. The opposite can also be done, _only_ allow certain requests using `allowResourceTypes` and `allowRequestPattern`.