Simmer 2 1/2 cups water and broth; keep warm. Heat oil in a saucepan over medium heat. Sauté onions 2 minutes. Add couscous. Cook 2 minutes; stir constantly. Stir in 1 cup broth mixture, rind, salt, and pepper; cook, stirring constantly, until liquid is nearly absorbed. Add remaining broth mixture, 1/2 cup at a time; stir constantly until each portion is absorbed before adding next. Add shrimp. Cook 2 minutes; stir constantly. Remove from heat; stir in cheese and parsley.