add doc

README.md

@@ -378,7 +378,7 @@ These examples incubate dotSCAD and dotSCAD refactors these examples. See [examp
 --|--
 [**polyhedra/tetrahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-tetrahedron.html) | Create a tetrahedron.
 [**polyhedra/hexahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-hexahedron.html) | create a hexahedron.
-polyhedra/octahedron | create a octahedron.
+[**polyhedra/octahedron**(radius[, detail])](https://openhome.cc/eGossip/OpenSCAD/lib3x-octahedron.html) | create a octahedron.
 polyhedra/dodecahedron | create a dodecahedron.
 polyhedra/icosahedron | create a icosahedron.
 polyhedra/superellipsoid | create a superellipsoid.

docs/lib3x-octahedron.md

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

src/polyhedra/octahedron.scad

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