I see the function to insert Endnote Marker and I assume that it applies to adding endnotes to a document but its not clear how you use it. The section on menus in the manual appears to stop at selection, and doesn’t cover any items below that in the edit menu.
A search in the manual didn’t reveal a “how to”.
Making footnotes is self evident but I don’t see anything about endnotes.
I’m making the assumption that you can have both footnotes and endnotes in a document. I’m also assuming that menu item doesn’t refer to the application Endnotes.
The Scrivener editor doesn’t differentiate between footnotes and endnotes. That decision is made when you use the Compile function to create your output document.
See the File -> Compile -> Footnotes and Comments pane, and its associated section in the manual, for further details, as different output formats support different options. Overall, Scrivener supports four different note streams: inline and inspector footnotes, inline annotations, and inspector comments. These can be included in or excluded from the output document in a variety of ways.
The <$–ENDNOTES–> placeholder just tells the Compile function where to place the endnotes. For example, if you have an Acknowledgments section or other back matter, you might want to place the endnotes in front of it, rather than at the very end of the text. But if you don’t have endnotes at all, this command does nothing. It’s discussed in more detail in the Placeholder Tags List, available from the Help menu.