mention touch_output

pages/Configuring/Keywords.md

@@ -113,6 +113,7 @@ force_no_accel, follow_mouse, float_switch_override_focus
 Properties that change names:
 ```plain
 touchdevice:transform -> touch_transform
+touchdevice:output -> touch_output
 ```
 
 Example config section:

pages/Configuring/Variables.md

@@ -177,6 +177,7 @@ _Subcategory `input:touchdevice:`_
 | name | description | type | default |
 |---|---|---|---|---|
 | transform | transform the input from touchdevices. The possible transformations are the same as [those of the monitors](../Monitors/#rotating-and-the-default-workspace) | int | 0 |
+| output | the output to bind touch devices. Empty means unset and will use the current / autodetected. | string | \[EMPTY\] |
 
 ### Per-device input config