extension for indicating layer status with leds

docs/extension_statusled.md

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+# Status LEDs
+
+Indicate which layer you are on with ah array of single leds.
+
+During startup the leds light up to indicte that the bootup is finished.
+
+For the time being just a simple consecutive single led
+indicator. And when there are more layers than leds it
+wraps around to the first led again.
+(Also works for a single led, which just lights when any
+layer is active)
+
+_Most of the code comes from the Mono color LED backlight extension_.
+
+## Enabling the extension
+
+To enable the extension you need to define a list of `led_pins`. It can be a list of a one, two or three pins.
+
+```python
+from kmk.extensions.statusled import statusLED
+import board
+
+statusLED = statusLED(led_pins=[board.GP0, board.GP1, board.GP2])
+keyboard.extensions.append(statusLED)
+```
+
+## [Keycodes]
+
+| Key           | Aliases | Description         |
+| ------------- | ------- | ------------------- |
+| `KC.SLED_INC` |         | Increase Brightness |
+| `KC.SLED_DEC` |         | Decrease Brightness |
+
+## Configuration
+
+All of these values can be set by default for when the keyboard boots.
+
+```python
+from kmk.extensions.led import AnimationModes
+led_ext = LED(
+    led_pin=led_pin,
+    brightness=30,
+    brightness_step=5,
+    brightness_limit=100,
+    )
+```