Attached documents when exporting to PDF

I propose two potential options for improving the export.

The first option is to allow users to select additional documents to attach when exporting a PDF. This would give users the flexibility to include relevant documents directly during the export process.

The second option is for the export engine to automatically detect externally linked documents within the main manual and incorporate those into the exported PDF. This would ensure that all referenced materials are included without requiring manual selection.

An ideal solution might be to offer users the choice between these two options or even the ability to utilize both simultaneously.