* readme.org: Update for unlinked references

readme.org

@@ -1,8 +1,14 @@
 * nroam
 
-nroam is a supplementary package for [[https://github.com/org-roam/org-roam][org-roam]] that replaces the backlink side buffer of Org-roam.  Instead, it displays org-roam backlinks at the end of org-roam buffers.
+nroam is a supplementary package for [[https://github.com/org-roam/org-roam][org-roam]] that replaces the backlink side buffer of Org-roam.  Instead, it displays org-roam backlinks—and unlinked references— at the end of org-roam buffers.
 
-[[file:screenshots/screenshot.png][file:screenshots/screenshot.png]]
+** Screenshots
+
+*** Backlinks
+[[file:screenshots/backlinks.png][file:screenshots/backlinks.png]]
+
+*** Unlinked references
+[[file:screenshots/unlinked-references.png][file:screenshots/unlinked-references.png]]
 
 * Rationale