The city has just released instructions for those Bostonians who wish to leave condolences to former Mayor Thomas M. Menino:City Hall will be open until 11:00 p.m. tonight. Flowers and mementos may be left in City Hall, inside the main City Hall entrance (City Hall Plaza side).By tomorrow, condolence books will be located in all neighborhood libraries (www.bpl.org/branches) and community centers (www.cityofboston.gov/BCYF/centers/).