The widow of Martin Luther King urged that Jan. 20, 1986, the first federal holiday honoring her late husband next year be a day of peace both in war zones and private homes. "I ask for a demonstration that peace is not just a dream, but a possibility, if only for one day," Coretta Scott King told a joint session of the state Senate and Assembly. Later in a meeting with Gov. George Deukmejian, Mrs. King told the Republican governor that she appreciated the "ethnic, religious and cultural diversity" of the state commission he appointed to celebrate her late husband's birthday, adding she wants it to be "a day all Americans can celebrate and call their own." Congress passed a law declaring the third Monday in January a federal holiday in honor of the slain civil rights leader.