With one of the most significant holidays on the Jewish calendar approaching, some synagogues around the country are posting volunteers in supermarket aisles.It’s part of a national program initiated several years ago to reach out to Jews who are buying matzos for Passover but do not belong to a house of worship.”The idea is, ‘Listen, everybody goes shopping,’ ” said Rabbi Aaron Schonbrun of Congregation Beth David in Saratoga, Calif. “Even your average Jewish person that may be vaguely aware that it’s Passover, or may not be aware it’s Passover, or is just in the supermarket.”Volunteers from his synagogue are setting up tables at two nearby supermarkets before Passover, which begins at sundown Wednesday. The practice is also taking place on Long Island, N.Y., and in Tucson, Ariz.; Seattle and elsewhere.It’s one of the ways Jewish leaders are grappling with the vast numbers of Jews who do not belong to a synagogue, along with shrinking numbers overall……..