How about add a completion for hello?

[Wu Zhenyu]

Hi! I use zsh and have a little knowledge about zsh completion.

Like this: (this file should be /usr/share/zsh/site-functions/_hello)

```
#compdef hello

_arguments -s '(- *)'{-h,--help}'[display this help and exit]' \
  '(- *)'{-v,--version}'[display version information and exit]' \
  {-t,--traditional}'[use traditional greeting]' \
  {-g,--greeting=}'[use TEXT as the greeting message]:TEXT'
```

How about add a completion for hello?

Thanks!

-- 
Best Regards
Wu Zhenyu

_hello
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