Fix backlight controls for dell laptop

etc/acpi/handler.sh

@@ -8,6 +8,12 @@ for_each_pa_user() {
 }
 
 case "$1" in
+    button/brightnessup)
+	for_each_pa_user sudo xbacklight -inc 10
+	;;
+    button/brightnessdown)
+	for_each_pa_user sudo xbacklight -dec 10
+	;;
     button/volumedown)
 	for_each_pa_user /etc/acpi/volume.sh -10%
 	;;

etc/udev/rules.d/backlight.rules

@@ -0,0 +1 @@
+ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video $sys$devpath/brightness", RUN+="/bin/chmod g+w $sys$devpath/brightness"

install_dotfiles.sh

@@ -149,6 +149,7 @@ if [ "${WORKSTATION}" -eq 1 ]; then
     install .config/darktable/darktablerc
     install -r usr/share/darktable/noiseprofiles.json
     install -r usr/share/lensfun/version_1/compact-sony.xml
+    install -r etc/udev/rules.d/backlight.rules
 fi
 
 if [ "${DEV}" -eq 1 ] && [ "${WORKSTATION}" -eq 1 ]; then