add doc

README.md

@@ -382,5 +382,5 @@ polyhedra/star | create a 3D star.
 [**polyhedra/hexahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_hexahedron.html) | create a hexahedron.
 [**polyhedra/octahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_octahedron.html) | create a octahedron.
 [**polyhedra/dodecahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_dodecahedron.html) | create a dodecahedron.
-polyhedra/icosahedron | create a icosahedron.
+[**polyhedra/icosahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_icosahedron.html) | create a icosahedron.
 [**polyhedra/superellipsoid**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_superellipsoid.html) | create a superellipsoid.

docs/lib3x-polyhedra_icosahedron.md

@@ -0,0 +1,22 @@
+# icosahedron
+
+Creates a icosahedron.
+
+**Since:** 3.2
+
+## Parameters
+
+- `radius` : Radius of the icosahedron.
+- `detail` : Default to 0. Setting this to a value greater than 0 adds vertices making it no longer a icosahedron.
+
+## Examples
+
+	use <polyhedra/icosahedron.scad>;
+
+	for(i = [0:5]) {
+		translate([i * 2, 0])
+			icosahedron(radius = 1, detail = i);
+	}
+
+![icosahedron](images/lib3x-polyhedra_icosahedron-1.JPG)
+

src/polyhedra/icosahedron.scad

@@ -1,3 +1,13 @@
+/**
+* icosahedron.scad
+*
+* @copyright Justin Lin, 2021
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib3x-polyhedra_icosahedron.html
+*
+**/
+
 use <geom_icosahedron.scad>;
 
 module icosahedron(radius, detail = 0) {