Fix @Config.Comment not working on subcategory Objects. Closes #3593

src/main/java/net/minecraftforge/common/config/ConfigManager.java

@@ -249,6 +249,7 @@ public class ConfigManager
         else if (ftype.getSuperclass() == Object.class) //Only support classes that are one level below Object.
         {
             String sub = (category.isEmpty() ? "" : category + ".") + getName(f).toLowerCase(Locale.ENGLISH);
+            cfg.getCategory(sub).setComment(comment);
             Object sinst = get(instance, f);
             for (Field sf : ftype.getDeclaredFields())
             {