Korean translation for README.md, README.rst file
[  ] : closes #xxxx
[  ] : tests added / passed
[  ] : passes git diff upstream/master --name-only -- '*.py' | flake8 --diff
[O] : whatsnew entry

We have translated some documents into Korean for Pandas Korean users. This is to make it easier for Koreans to read documents and use Pandas more easily and conveniently.

We have translated the README.md and doc / README.rst files into README_KR.md and README_KR.rst files.

Please check this and if you think that you need to translate more documents into Korean, please comment.