add comment about problem_space

src/complexagent.rs

@@ -79,6 +79,8 @@ impl Move {
     }
 }
 
+/// Take a [`Board`] and a [`Piece`] color and give all possible moves for that color on the board
+/// Returns a Boxed iterator to be used in other logic
 fn problem_space(board: &Board, color: Piece) -> Box<dyn Iterator<Item = Move> + '_> {
     Box::new(
         board