Ommit <main class> it command line output with no arguments

If I run the batch script with no arguments, I get:

```
C:\Users\trent\utPLSQL-cli\bin>utplsql.bat
Usage: <main class> [command] [command options]
  Commands:
    run      run tests
```

I think the `<main class>` is not an actual part of required input, right?