config/graphical-session: hint to font installation for compositors

Some Wayland compositors don't include fonts by default, so describe tersely
how they should be installed

src/config/graphical-session/fonts.md

@@ -1,5 +1,8 @@
 # Fonts
 
+[xbps-query(1)](../../xbps/index.md#finding-files-and-packages) can be used to
+list font-related packages. Many fonts are packaged with the `font-` prefix.
+
 To customize font display in your graphical session, you can use configurations
 provided in `/usr/share/fontconfig/conf.avail/`. To do so, create a symlink to
 the relevant `.conf` file in `/etc/fonts/conf.d/`, then use

src/config/graphical-session/wayland.md

@@ -30,6 +30,9 @@ Void Linux currently packages the following Wayland compositors:
 - labwc: a window-stacking compositor, inspired by Openbox
 - Qtile: a dynamic tiling Wayland compositor (via qtile-wayland)
 
+Some compositors don't depend on any [fonts](./fonts.md), so you have to install
+them manually for most applications to work.
+
 ### Video drivers
 
 Both GNOME and KDE Plasma have EGLStreams backends for Wayland, which means they