Avoid validation problem fot keybinding file

README.md

@@ -65,7 +65,25 @@ sway_inputs:
 
 ### Keybinding
 
-Manage keybinding
+Keybinding require two variables: `sway_keys_variables` and `sway_keybindings`.
+ `sway_keys_variables` defined variables for keybinding. Because configuration
+ file checking throw an error if the first argument of `bindsym` contains a
+ variable not defined is the file (because `10-variables.config` is not included
+ when testing)
+
+```yaml
+sway_keys_variables:
+ - name: '$left'
+   value: 'h'
+ - name: '$down'
+   value: 'j'
+ - name: '$up'
+   value: 'k'
+ - name: '$right'
+   value: 'l'
+ - name: '$mod'
+   value: 'Mod4'
+```
 
 ```yaml
 sway_keybindings: