[lldb] Fix `target stop-hook add` help output
The help output for `target stop-hook add` references non-existing
option `--one-line-command`. The correct option is `--one-liner`:
```
-o <one-line-command> ( --one-liner <one-line-command> )
Add a command for the stop hook. Can be specified more than once,
and commands will be run in the order they appear.
```
This commit fixes the help text.
rdar://152730660
