Update .changeset/nervous-steaks-provide.md

Co-authored-by: Josh Winn <965114+jawinn@users.noreply.github.com>

Author: cdransf

.changeset/nervous-steaks-provide.md

@@ -2,4 +2,4 @@
 "@spectrum-css/treeview": patch
 ---
 
-Use custom property in place of direct value when defining mod.
+Use the already defined custom property `--spectrum-treeview-item-border-color-quiet-selected` in place of the direct value. The border color value remains the same.