This plugin shows how to insert content or another document in current documents.
It is called "Example insert content & document" in the interface and isn't installed by default in cloud, self-hosted and desktop version of ONLYOFFICE editors.
- Open the Plugins tab and press "Example insert content & document" (all content will be added at the current cursor position).
If you need more information about how to use or write your own plugin, please see this https://api.onlyoffice.com/plugin/basic