This 11-year-old just wrote a book on bitcoin that hopefully a kid can understand Andrew Courey, a middle school student in Massachusetts, recently published a 57-page book on bitcoin. He did the research when he wasn't in school, playing sports or working on mobile apps. Like most sixth graders, Andrew Courey is usually playing sports and toying with his iPhone when he's not in school. But unlike most other 11-year olds, he's also an expert on bitcoin. Courey is the…