Add Korean translation (#300)

* add ko.po

* translate ko(~23.01.19)

* change speaker-note ko

* change id

* translate ko(~23.01.20)

* ~day3 keynote

* draft done to f3446a91

* add @jiyongp comments of upstream PR #276.

* sync & apply review comments(upstream)

sync 585509bb

* After 10000 line apply review comments(upstream)

* chgange build.yml

* Fix the inconsistent newline character problem for the KO translation

If a msgid does not end with the newline character, so should the
msgstr.

Test: msgfmt --statistics -o /dev/null po/ko.po
No error, but shows `1085 translated messages, 675 untranslated
messages.`

---------

Co-authored-by: Evan kim(cli) <keispace.kyj@gmail.com>

.github/workflows/build.yml

@@ -84,6 +84,7 @@ jobs:
       matrix:
         language:
           - da
+          - ko
     env:
       MDBOOK_BOOK__LANGUAGE: ${{ matrix.language }}
       MDBOOK_PREPROCESSOR__GETTEXT__PO_FILE: po/${{ matrix.language }}.po