WASHINGTON (Reuters) - A 6-year-old U.S. girl will become the youngest contestant ever in the Scripps National Spelling Bee after winning a regional competition in Virginia. Lori Anne Madison, of Woodbridge, Virginia, won the Prince William County spelling contest earlier this month, beating out 21 top elementary and middle school competitors. Her winning word: "vaquero," a word of Spanish origin meaning cowboy. "My parents quiz me. I read lists and I have a really good memory," Madison, who is home-schooled, told Fox's WTTG-TV, a Washington-area station. Madison was believed to be the youngest competitor ever, the Cincinnati-based National Spelling Bee...