The rumor is true: Ming Tsai tells us he is opening a Chinese restaurant on A Street. But that’s all the Blue Ginger chef will say. “Details to follow. . .:),” he wrote in an e-mail over the weekend. The “Simply Ming” host would be the latest high-profile foodie to bet on Fort Point, joining Joanne Chang and Barbara Lynch. . . . Lynch, by the way, has just announced the creation of the Barbara Lynch Foundation, a nonprofit she says is aimed at making Boston healthier, with an emphasis on nutrition, exercise, and community involvement.