fix(disl): copy disl%reach_bottom into disbase%bot (MODFLOW-USGS#1662)

* does not account yet for idomain

src/Model/SurfaceWaterFlow/swf-disl.f90

@@ -685,6 +685,11 @@ subroutine grid_finalize(this)
         node = node + 1
       end do
     end if
+    !
+    ! -- Move reach_bottom into bot
+    do node = 1, this%nodesuser
+      this%bot(node) = this%reach_bottom(node)
+    end do
 
     ! -- Return
     return