Fix pac-help output. Remove first ocurrence of '-'.

Before:
-------

```
$ pac
usage:
  pac <command> [...]

commands:
  ...
  pac ls outdated
```

Now:
----

```
$ pac
usage:
  pac <command> [...]

commands:
  ...
  pac ls-outdated
```
Merge pull request #2 from frodsan/fix_pac_help

Fix pac-help output. Remove first ocurrence of '-'.