Add an option to hide the “Click and drag to make a selection” text in Spectacle

This is a feature request for Spectacle.

Please add an option to hide the “Click and drag to make a selection” text shown in rectangular region mode.

The current behavior is useful for new users, but the text can be distracting for users who already know how the tool works.

It would be nice to have a simple option to disable or hide this helper text.