Does indeed look like sunburn. Doritis are similar to Phalaenopsis in their light requirements and can not handle direct sun, especially in the hottest part of the day. Find a shaded location with bright, indirect light.
Water the plant thoroughly and then do not water again until the plant is nearly dry, but keep the plant more hydrated while a bloom spike is developing. You may lose some of the leaves that were burned and you may have to cut parts of them off if they start to rot. I use a single edge razor blade. Dust the cut edges with powdered cinnamon or a fungicide. The damaged leaves will not recover, but, given proper care, the plant will produce healthy new leaves to take their place, and the plant will recover.