IonicBond
This is already an intersection and U turns are there by default. If you ever need to edit turn restrictions, in iD you can select a point from a road, scroll down, and you should see a little window with a diagram of the roads attached to or near that point labeled "turn restrictions". Click on each road in that diagram and you can edit where you're allowed to go from what directions there. U turns are usually shown there on single roads as a curved arrow icon, but since this is a split road it's not explicitly labeled as that, instead you go north on Nacogdoches Road, then at this intersection turn west on Danbury Street and immediately turn south back on Nacogdoches Road.