add doc

README.md

@@ -234,7 +234,7 @@ See [examples](examples).
 - [matrix/m_determinant](https://openhome.cc/eGossip/OpenSCAD/lib2x-m_determinant.html)
 
 ### Voronoi
-- voronoi/vrn2_from
+- [voronoi/vrn2_from](https://openhome.cc/eGossip/OpenSCAD/lib2x-vrn2_from.html)
 - voronoi/vrn2_space
 - voronoi/vrn2_cells_from
 - voronoi/vrn2_cells_space

docs/lib2x-vrn2_from.md

@@ -0,0 +1,40 @@
+# vrn2_from
+
+Creats a [Voronoi diagram](https://en.wikipedia.org/wiki/Voronoi_diagram) from a list of points. 
+
+**Since:** 2.4
+
+## Parameters
+
+- `points` : Points for each cell. 
+- `spacing` : Distance between cells. Default to 1.
+- `r`, `delta`, `chamfer` : The outlines of each cell can be moved outward or inward. These parameters have the same effect as [`offset`](https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Transformations#offset). 
+- `region_type` : The initial shape for each cell can be `"square"` or `"circle"`. Default to `"square"`.
+
+## Examples
+
+    use <voronoi/vrn2_from.scad>;
+
+    points = [for(i = [0:50]) rands(-20, 20, 2)];
+
+    vrn2_from(points);
+    translate([60, 0, 0]) 
+        vrn2_from(points, region_type = "circle");
+
+![vrn2_from](images/lib2x-vrn2_from-1.JPG)
+
+    use <voronoi/vrn2_from.scad>;
+    use <hollow_out.scad>;
+
+    xs = rands(0, 40, 50);
+    ys = rands(0, 20, 50);
+
+    points = [for(i = [0:len(xs) - 1]) [xs[i], ys[i]]];
+
+    difference() {
+        square([40, 20]);
+        vrn2_from(points);
+    }
+    hollow_out(shell_thickness = 1) square([40, 20]);
+    
+![vrn2_from](images/lib2x-vrn2_from-2.JPG)