Task Pane - Make adding Subtasks/Subsections more discoverable and consistent with adding Tasks

Instead of just + Add subtask : This should be a control like:
(but change “Task” to “Subtask” and change “Section” to “Subsection”) so you can easily add a subtask or subsection (and milestone eventually) and be reminded of the shortcuts. Maybe include both at top and bottom of Subtasks list if more than a few subtasks present.