A D Augmented (Daug) chord contains the notes D, A#, F#. It is built from the augmented formula 1 - 3 - ♯5, with D as the root.
How do I get to D augmented from an open D chord?
Only one note changes. In open D you fret the G string at the 2nd fret; for Daug that note moves up to the 3rd fret, so the shape becomes x-x-0-3-3-2. Everything else stays put, which is why Daug works so naturally as a passing chord between D and whatever comes next.