Update bitcoin_ko_KR.ts

1. Fix some mistakes(typo, omission, spacing).
2. Re-adjust sentences to proper form.
3. Replace translation of certain words to better one.
4. Update legacy translations of upstream.

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I commit this first, and will commit another updates after 'translation resources update' that I waiting.

The translation of "Dogecoin" is replaced by "도지코인".
So, It's not confused. \ㅇㅅㅇ/

thanks.