I’ll be writing all about BEA Chicago in my first Monday opinion column on the self-publishing advice blog, shortly. But I wanted to bring you guys this highlight. Mavis Staples was there, promoting her book and giving a secret concert. I couldn’t go because I was at the Goodreads dinner that evening (also a wonderful event) but Christine Monroe from Kobo assures me she was completely fabulous — as ever. Mavis is super busy at the moment, what with promoting her book,  a new documentary and finishing Pops Staples (her dad’s) posthumous album. “Mavis sang ‘Friendship’ from it at the show, and it was so…