Doris Diether, one of the city’s longest-serving community board members, shared the spotlight at the book signing for Brandon Stanton’s new “Humans of New York Stories” at Barnes & Noble’s Union Square store on Tuesday evening. Diether, 86, shares a page in the book with her Washington Square Park pal Ricky Syers, who turned her into a virally “trending” Internet phenomenon after he created a Little Doris marionette of her. After she and Syers cabbed it over to the bookstore, Big Doris — who is nobody’s puppet — with her trademark chuckle, characteristically took all the hoopla in stride as she signed copies of the guaranteed bestseller. Stanton started his blog in 2010, crisscrossing the city, capturing New Yorkers and their stories, even going on to meet with President Obama. The new hardcover book, with 400 full-color photos, is $17.99 in hardcover and $14.99 on Kindle.