feat: init maximum depth of binary tree

Author: bujosa

src/easy/maximum_depth_of_binary_tree.rs

@@ -13,6 +13,7 @@ pub mod length_of_last_word;
 pub mod linked_list_cycle;
 pub mod longest_common_prefix;
 pub mod max_depth_of_binary_tree;
+pub mod maximum_depth_of_binary_tree;
 pub mod merge_sorted_array;
 pub mod merge_two_sorted_lists;
 pub mod min_stack;