add doc

docs/lib2x-vx_bezier.md

@@ -0,0 +1,33 @@
+# vx_bezier
+
+Given 4 control points, returns voxel-by-voxel points of Bézier Curve .
+
+## Parameters
+
+- `p1` : The 1st control point.
+- `p2` : The 2nd control point.
+- `p3` : The 3rd control point.
+- `p4` : The 4th control point.
+
+## Examples
+
+	use <voxel/vx_bezier.scad>;
+
+	t_step = 0.05;
+	width = 2;
+	
+	p1 = [0, 0, 0];
+	p2 = [30, 15, 25];
+	p3 = [-35, 20, -20];
+	p4 = [10, 40, 9];
+	
+	points = vx_bezier( 
+	   p1, p2, p3, p4
+	);
+	
+	for(p = points) {
+		translate(p)
+		    cube(1);
+	}     
+
+![vx_bezier](images/lib2x-vx_bezier-1.JPG)