fix comment typo

src/Tools/babylon.tools.ts

@@ -589,7 +589,7 @@ module BABYLON {
         /**
          * Returns an array of the given size filled with element built from the given constructor and the paramters
          * @param size the number of element to construct and put in the array
-         * @param itemBuilder a callback responsable for creating new instance of item. Called once per array entry.
+         * @param itemBuilder a callback responsible for creating new instance of item. Called once per array entry.
          * @returns a new array filled with new objects
          */
         public static BuildArray<T>(size: number, itemBuilder: () => T): Array<T> {