add documentation

docs/api/core/Object3D.html

@@ -170,6 +170,14 @@
 		<div>
 		Gets first child with name matching the argument. Searches whole subgraph recursively if *recursive* is true.
 		</div>
+		
+		<h3>.getDescendants( [page:Array returnValue] )</h3>
+		<div>
+		returnValue - optional argument that returns the the array with descendants.<br />
+		</div>
+		<div>
+		Searches whole subgraph recursively to add all objects in the returnValue.
+		</div>
 
 		<h3>.updateMatrix()</h3>
 		<div>