Thrill to the vibrant gymnastics grace of Gabby Douglas, the fierce tennis power of Serena Williams, the skill of Kayla Harrison in winning the first gold for an American woman in judo. Led by Missy Franklin and Rebecca Soni and others, the U.S. women’s swimming team as of Monday had harvested eight gold medals, three silver and three bronze. The U.S. women’s beach volleyball team, the basketball team and the soccer team are still in the hunt. American women are leading the way this Olympics. It’s worth remembering why. Rules matter. Opportunity is vital. A level playing field, clear goals, …