[#2145] fix output dir

Author: remkop

picocli-codegen/src/test/java/picocli/codegen/docgen/manpage/Issue2145.java

@@ -18,7 +18,7 @@ static class Documentation {
 
     @Test
     public void testManPageGenAsSubcommand() {
-        int result = new CommandLine(new Documentation()).execute("gen-manpage", "-dout", "-v");
+        int result = new CommandLine(new Documentation()).execute("gen-manpage", "-dbuild", "-v");
         assertEquals(0, result);
     }
 }