README edit

README.md

 Mic sensitive neopixel/WS2811 strip.
 
-Color component of HSV is a slowly fading raingbow.
+Color component of HSV is a slowly color-cycling rainbow.
 Value compomenent depends on current and short history levels.
 
 I zip-tie this to my protest marching drum ([video](https://reshet.social/@zzzen/112031848137797168)).