Add keywords

keywords.txt

+OctoWS2811	KEYWORD1
+setPixel	KEYWORD2
+getPixel	KEYWORD2
+show	KEYWORD2
+busy	KEYWORD2
+numPixels	KEYWORD2
+WS2812_RGB	LITERAL1
+WS2812_RBG	LITERAL1
+WS2812_GRB	LITERAL1
+WS2812_GBR	LITERAL1
+WS2812_BRG	LITERAL1
+WS2812_BGR	LITERAL1