Add comments for IntructionPointer's move function

src/pointer.ts

@@ -100,6 +100,9 @@ export class InstructionPointer {
         this.changeDirection(Object.keys(this.directions)[Math.floor(Math.random() * 4)] as OrdinalDirection);
     }
 
+    /**
+     * Move the InstructionPointer one step in its current direction
+     */
     public move() {
         this.X += this.currentVector[0];
         this.Y += this.currentVector[1];