docs: Power-off fix texts cover every affected kernel, not just 7.2

lib/menu.sh

@@ -33,7 +33,7 @@ declare -A LABEL=(
     [launcher]="Steamify shortcut: the app on the desktop, Steamify Terminal in the launcher"
     [cec]="HDMI-CEC: use Steam with the TV remote, TV on/off with the PC (experimental)"
     [machine]="Steam Machine support: LED bar driver, hardware settings in Steam"
-    [poweroff]="Power-off fix: stays off after shutting down, on every kernel"
+    [poweroff]="Power-off fix: the Steam Machine stays off after shutting down"
     [kpin]="Pin the kernel to $PINNED_KERNEL_VER (no longer needed: untick for CachyOS's current kernel)"
     [hdmi]="HDMI refresh boost: highest refresh your HDMI display runs"
     [bios]="Update BIOS"