Refactor nibble / update to match build docs (#620)

* feat(nibble): add underglow support for nice_nano builds

* feat(nibble): add encoder to top, left most column to match standard assembly documentation

* refactor(nibble): add layer labels

* feat(nibble): add support for optional display ; off by default

* feat(nibble): add README

* fix(nibble): adjust oled rotation for easier reading

* fix(nibble): add additional note about enabling oled

* refactor(nibble): convert keymap to use tabs instead of spaces

* refactor(nibble): enable oled in dts/overlay by default

* refactor(nibble): cleanup alignment and formatting in nibble keymap

* refactor(nibble): re-align top most row of keymap to be sensible

* refactor(nibble): cleanup kscan map alignment

* refactor(nibble): indent first row of map/transform to properly align with physical columns

* fix(nibble): remove dangling code block from readme

Co-authored-by: KemoNine <mcrosson@kemonine.info>

app/boards/shields/nibble/boards/nice_nano.conf

@@ -0,0 +1,4 @@
+# Enable underglow
+CONFIG_ZMK_RGB_UNDERGLOW=y
+# Use the STRIP config specific to the LEDs you're using
+CONFIG_WS2812_STRIP=y

app/boards/shields/nibble/boards/nice_nano.overlay

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+&spi1 {
+	compatible = "nordic,nrf-spim";
+	status = "okay";
+	mosi-pin = <11>;
+	// Unused pins, needed for SPI definition, but not used by the ws2812 driver itself.
+	sck-pin = <5>;
+	miso-pin = <7>;
+
+	led_strip: ws2812@0 {
+		compatible = "worldsemi,ws2812-spi";
+		label = "WS2812";
+
+		/* SPI */
+		reg = <0>; /* ignored, but necessary for SPI bindings */
+		spi-max-frequency = <4000000>;
+
+		/* WS2812 */
+		chain-length = <10>; /* number of LEDs */
+		spi-one-frame = <0x70>;
+		spi-zero-frame = <0x40>;
+	};
+};
+
+/ {
+	chosen {
+		zmk,underglow = &led_strip;
+	};
+};

app/boards/shields/nibble/boards/proton_c.conf

@@ -0,0 +1 @@
+CONFIG_SENSOR=y