Add doc in step

Author: foxtran

fortran/solver/src/step.f90

@@ -1,15 +1,27 @@
 module step_mod
     implicit none
     private
+
+    !> @brief step in plan
     type :: step_t
-        integer(1) :: room_out = -1
-        integer(1) :: door_out = -1
-        integer(1) :: room_in = -1
+        integer(1) :: room_out = -1 !< starting room
+        integer(1) :: door_out = -1 !< starting door
+        integer(1) :: room_in = -1  !< entered room
     contains
         procedure :: show
     end type step_t
+
     public :: step_t
 contains
+
+    !>
+    !> @brief prints structure of step_t to stdout
+    !>
+    !> @param[in] step - step_t object
+    !>
+    !> @author foxtran
+    !> @date   Sep 8, 2025
+    !>
     subroutine show(step)
         class(step_t), intent(in) :: step
         write(6, '(I3," ",I0," ",I3)') step%room_out, step%door_out, step%room_in