Update cheatsheets

linux/backlight_control

@@ -0,0 +1,21 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# backlight_control
+
+> Control a linux machine's backlight using percentage values.
+> More information: <https://github.com/Hendrikto/backlight_control>.
+
+- Increase/decrease the backlight by a specific percent count:
+
+`backlight_control {{+|-}}{{5}}`
+
+- Set the backlight strength to a specific percent count:
+
+`backlight_control {{90}}`
+
+- Display help:
+
+`backlight_control`