config/graphical-session/wayland: add niri

closes: #843 [via git-merge-pr]

Author: Babkock

src/config/graphical-session/wayland.md

@@ -27,6 +27,7 @@ Void Linux currently packages the following Wayland compositors:
 - Hikari: a stacking compositor with some tiling features
 - Cage: a Wayland kiosk
 - River: a dynamic tiling Wayland compositor
+- Niri: a scrolling-tiling Wayland compositor
 - labwc: a window-stacking compositor, inspired by Openbox
 - Qtile: a dynamic tiling Wayland compositor (via qtile-wayland)