Adding Text After Chapters and Scenes
The Back Matter section is the book text AFTER any chapters or scenes.
If you want to add sections to your book which are shown before the main text, then add this in a 'Back Matter' section
Give each front matter section a title such as 'Epilogue' or 'Afterword' etc.
This article has a good description of back matter
The Back Matter Section
This is a good place to add an epilogue, afterword, appendix, etc.