Update README.md

codelast · codelast · commit b7bf5a001c6b · 2015-10-31T20:54:11.000+08:00
diff --git a/gpio/led/README.md b/gpio/led/README.md
@@ -2,3 +2,8 @@ Demos on how to:
 * blink a LED
 * control a LED through a button(pressed or not)
 * control the brightness of a LED through PWM
+
+该目录下的程序演示了：
+* 如何用树莓派控制LED闪烁
+* 如何通过一个外部按钮的开关来控制LED的亮灭
+* 如何通过PWM来控制LED的亮度
