A decade after he first took a knee during the national anthem, Colin Kaepernick will be publishing his life story. The activist and former San Francisco 49ers quarterback has completed “The Perilous Fight,” to come out Sept. 15 through the Hachette Book Group imprint Legacy Lit. Kaepernick, who has not played in the NFL since 2016, said in a statement that he wanted to offer context for what led to his taking a knee.