China’s market watchdog is initiating a series of moves to tamp down runaway competition in the meal delivery arena, spurring a rally in shares of sector leaders Meituan and JD.com Inc.The State Administration for Market Regulation drafted rules that include a cap on fees charged to restaurants and greater transparency around subsidy and discounting campaigns. The idea is to promote more “orderly” competition and protect merchants caught in the crossfire, according to a report by national broadc...