BOSTON — Bill Moyers, the journalist and veteran PBS personality who has come out of retirement at least twice to mount new weekly productions, announced Friday that he will be back in January with a 30-minute show. Three weeks ago, Moyers announced his decision to end production of Moyers & Company early next year, citing the end of two-year funding commitments. But the response from viewers and underwriters prompted him to reconsider, according to Executive Producer Judy Doctoroff, who spoke to public TV programmers during American Public Television’s Fall Marketplace. APT, which is showcasing new program offerings for local pubTV stations this week, distributes the series nationally. Moyers’ production team had already floated their proposal to keep the show going with station-based programmers, Doctoroff said in an interview.