docs: Add info about maintainer

Author: 2martens

src/main/java/org/opentripplanner/openstreetmap/tagmapping/HamburgMapper.java

@@ -8,6 +8,8 @@
  * @see GermanyMapper
  * @see OsmTagMapper
  * @see DefaultMapper
+ * 
+ * @author Maintained by HBT (geofox-team@hbt.de)
  */
 public class HamburgMapper extends GermanyMapper {
 

src/test/java/org/opentripplanner/openstreetmap/tagmapping/HamburgMapperTest.java

@@ -9,6 +9,9 @@
 import org.junit.jupiter.params.provider.ValueSource;
 import org.opentripplanner.openstreetmap.model.OSMWithTags;
 
+/**
+ * @author Maintained by HBT (geofox-team@hbt.de)
+ */
 public class HamburgMapperTest {
 
   private HamburgMapper mapper;