There is a number every Celtics fan in Acton already knows: 00. It is the jersey number that Robert Parish, known throughout New England simply as “The Chief”, wore during his 14 seasons with the Boston Celtics. That number now hangs in the rafters of TD Garden. And on Tuesday night, Parish himself walked through the door of The Silver Unicorn Bookstore at 12 Spruce Street in West Acton Village to a standing room only crowd. The occasion was the launch of his new memoir, “The Chief” (Triumph Books), written with Seattle-based journalist Jake Uitti. For fans of Celtics basketball,…