[edit] append usage and more to readme.

README.md

@@ -1 +1,20 @@
 # glsl-convert-color
+
+this is the function that convetts RGB to HSV. or is its opposite.
+
+## Quote source
+
+http://lolengine.net/blog/2013/07/27/rgb-to-hsv-in-glsl
+
+## install
+
+```
+npm i git://github.com/ykob/glsl-convert-color.git
+```
+
+## usage
+
+```
+#pragma glslify: convertHsvToRgb = require(glsl-convert-color/convertHsvToRgb);
+#pragma glslify: convertRgbToHsv = require(glsl-convert-color/convertRgbToHsv);
+```