Yes, those are appropriate cleaning instructions for the Ocean Aquaria artificial corals. The Ocean Aquaria corals are cast in molds, and the Dawn dish soap will clean off any of the mold-release compound or other undesirable residues from the artificial corals, which could be harmful to marine fish and invertebrates.
Just be sure to rinse off all the artificial corals thoroughly under running water when you are finished cleaning them with the Dawn dish soap and water. Keep the water running, and when you are confident you have removed any traces of the dish soap, repeat the rinsing process under running water once more to be on the safe side. Then allow the cleaned corals to air dry thoroughly in the sunlight outdoors, and they will be ready to place in your aquarium.
Best wishes with all your fishes, Ellenor!
Pete Giwojna, Ocean Rider Tech Support