Add limitation for self-signed certificates

Author: MxMurshed

content/en/docs/appstore/use-content/platform-supported-content/modules/document-generation.md

@@ -26,6 +26,7 @@ The [PDF Document Generation](https://marketplace.mendix.com/link/component/2115
 
 * The maximum file size is 25 MB per document. If your document exceeds this limit, the action will result in an exception. We recommend compressing high-resolution images to reduce their file size.
 * If your app is configured to [restrict access for incoming requests](/developerportal/deploy/access-restrictions/) using client certificates, our cloud service will not be able to reach your app and the module will not work properly.
+* If your app is using a custom domain, we require that you configure a custom domain certificate (an SSL/TLS certificate) signed by a trusted public authority, including all intermediate certificates if applicable. Self-signed certificates will cause the service to fail. See [Obtaining a new signed certificate](/developerportal/deploy/custom-domains/#obtaining-a-new-signed-certificate) for more details.
 * We use a fixed 30 second timeout for the page to finish loading and rendering. A timeout exception is thrown if the page content did not finish loading within 30 seconds.
 * Widgets or add-ons for your `index.html` file that perform long polling network requests are not supported. The document generation service waits until there are no more pending network requests.
 * Some widgets, such as the [Charts](/appstore/widgets/charts/) widget, might be rendered inconsistently in the generated PDF due to factors like animation.