Heather Donahue, best known as the actress from The Blair Witch Project, has written a book. Now this happens all the time, the once-famous-people-writing-books thing. And often the result is some cookie-cutter “memoir” of which the kindest remark you might make is that it has paid some deserving freelancer’s rent for six months. But Heather Donahue’s story caught my eye, regardless, because her book, Growgirl, was said to be about her quitting acting to grow pot. Medical marijuana, of course, all sanctioned by California law, but pot nonetheless, and, being self-interestedly attracted to stories of people who do about-faces in their careers in their early 30s, I was intrigued. [...]