bug#15447: (quail-help "korean-hangul") generates errors.

[Eli Zaretskii]

> Date: Sun, 22 Sep 2013 18:53:25 +0900
> From: crocket <crockabiscuit@gmail.com>
> 
> The error trace is shown below.
> 
> Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
>   quail-help("korean-hangul")

quail-help gives help on quail _packages_, and korean-hangul is not a
package, it's an input method.

Try this instead:

  C-u C-\ korean-hanja RET
  C-\
  M-: (quail-help "korean-hanja") RET

This works because korean-hanja is a Leim package.