Add tip to set keyboard layout per device

Guides/keyboard.md

@@ -0,0 +1,21 @@
+# Keyboard
+
+Tips to set up keyboard.
+
+## Persistent config
+
+See `Install/keyboard-custom` script.
+
+## On the fly
+
+List devices with
+
+```sh
+xinput list
+```
+
+and get id. Then set up with :
+
+```sh
+setxkbmap -device 13 -layout us
+```