MADRID (Reuters) – A Spanish-language version of “Spare”, the much-awaited memoir of Britain’s Prince Harry, went on sale in book stores in Spain on Thursday, days ahead of its official launch date. The book reveals details about Harry’s relationship with his father, King Charles, his elder brother, Prince William, and other members of the British royal family that have never previously been published. As is usual for the royal family, spokespeople for Charles and William have declined to comment. Following are some of the key details outlined in the book: BRAWL WITH BROTHER Harry says his bro…