Korean translation: stdout stderr and redirection

Hello,

Here is Korean translation of
"Standard output, standard error and command line redirection".

This is not-yet-published article so I couldn't know which folder this translation should be in. I chose pages/ folder in this pull request.

In addition, I fixed invalid tag and a typo in English version.
And I think "leave out the word STDERR" should be "leave out the word STDOUT".
Would you please check English version, because I might be wrong.


Thank you.
G.Y.Park