anchor.diff:  Applications that call `System.exit` need to configure the `exitCodeListHeading` and `exitCodeList` annotation attributes.
   For example:
   
  -```java
  +.Java
  +[source,java,role="primary"]
  +----
   @Command(mixinStandardHelpOptions = true,
  -        exitCodeListHeading = "Exit Codes:%n",
  -        exitCodeList = {
  -            " 0:Successful program execution",
  -            "64:Usage error: user input for the command was incorrect, " +
  +         exitCodeListHeading = "Exit Codes:%n",
  +         exitCodeList = {
  +             " 0:Successful program execution",
  +             "64:Usage error: user input for the command was incorrect, " +
  +                     "e.g., the wrong number of arguments, a bad flag, " +
  +                     "a bad syntax in a parameter, etc.",
  +             "70:Internal software error: an exception occurred when invoking " +
  +                     "the business logic of this command."})
  +class App {}
  +new CommandLine(new App()).usage(System.out);
  +----
  +
  +.Kotlin
  +[source,kotlin,role="secondary"]
  +----
  +@Command(mixinStandardHelpOptions = true,
  +         exitCodeListHeading = "Exit Codes:%n",
  +         exitCodeList = [
  +             " 0:Successful program execution",
  +             "64:Usage error: user input for the command was incorrect,"  +
                       "e.g., the wrong number of arguments, a bad flag, " +
                       "a bad syntax in a parameter, etc.",
  -            "70:Internal software error: an exception occurred when invoking " +
  -                    "the business logic of this command."})
  +             "70:Internal software error: an exception occurred when invoking " +
  +                    "the business logic of this command."])
   class App {}
  -new CommandLine(new App()).usage(System.out);
  -```
  +fun main(args: Array<String>) : Unit = CommandLine(App()).usage(System.out)
  +----
   
   This will print the following usage help message to the console:
   
  
positive.code:   or:  ln [OPTION]... -t DIRECTORY TARGET...  (4th form)
  ----
  To produce a synopsis like the above, specify the literal text in the `customSynopsis` attribute:
  [source,java]
  ----
  @Command(synopsisHeading = "", customSynopsis = {
          "Usage: ln [OPTION]... [-T] TARGET LINK_NAME   (1st form)",
  
negative.code: }
  ----
  
  .Kotlin
  [source,kotlin,role="secondary"]
  ----
  import picocli.CommandLine.Model.UsageMessageSpec.SECTION_KEY_COMMAND_LIST_HEADING
  import picocli.CommandLine.Model.UsageMessageSpec.SECTION_KEY_AT_FILE_PARAMETER
  // ...
  
  @Command(name = "myapp", showAtFileInUsageHelp = true,
           mixinStandardHelpOptions = true, description = ["Example command."])
  class MyApp {
      @Parameters(description = ["A file."]) lateinit var file: File
  
      companion object {
          @JvmStatic
          fun main(args: Array<String>) {
              val cmd = CommandLine(MyApp())
              val copy: MutableList<String> = ArrayList(cmd.helpSectionKeys)
              copy.remove(SECTION_KEY_AT_FILE_PARAMETER)
              copy.add(copy.indexOf(SECTION_KEY_COMMAND_LIST_HEADING), SECTION_KEY_AT_FILE_PARAMETER)
              cmd.helpSectionKeys = copy
              cmd.usage(System.out)
          }
      }
  }
  ----
  
  The resulting usage help message shows the `@<filename>` entry has moved to the bottom, following the options list:
  
  ----
  