"Creative Government Leadership," says a headline in the National Endowment for the Arts' glossy new booklet: "Baltimore: the Arts in a Proud City." According to the booklet, "The progress of Baltimore's renaissance owes much to the enlightened attitude of its municipal government. Mayor William Donald Schaefer describes his administration's all-inclusive approach: '. . . If we cut art and culture, we would be destroying our society.' He insists that the welfare of the city is indivisible--cultural and economic development are interdependent. Schaefer's administration has incorporated the arts into city planning . . . As Dr. Robert P. Bergman, director of the Walters Art Gallery points out, 'Most politicians have to be convinced that artistic quality and economic prosperity go hand in hand. Not Schaefer.' " The 32-page booklet, which will be distributed all over the country at taxpayer expense, includes a picture of Schaefer walking with an art college president. Arts Endowment chairman Francis S.M. Hodsoll went to Baltimore the other day for a press conference and presented Schaefer with a copy of the booklet, announcing that it is the first in a series of booklets planned to focus attention on cities "in which durable partnerships have been built between the arts and the community, enhancing both." Schaefer is a Democrat. Maryland went 47 percent for Carter and 44 percent for Reagan last time around.