Heat grill. Fold four 18-inch-long pieces of foil in half; unfold and coat inside with cooking spray. Place 2 cups spinach in center of 1 half of each piece of foil. Combine couscous with ¼ cup water; divide evenly among packets, placing on top of spinach. Combine shrimp, ¼ cup cilantro, oil and ½ teaspoon salt in a bowl. Divide shrimp evenly among packets, placing next to couscous. Fold foil to close and crimp edges to seal; place on grill; close lid; cook until packets are fully puffed, 10 minutes. Combine remaining ¼ cup cilantro with remaining ¼ teaspoon salt, mango, avocado, tomato, onion, jalapeño and lime juice in a bowl. Carefully cut foil to open; stir contents; garnish with salsa before serving.
