Add button to select all text in a preformatted block

[JammyDodger]

이제 코어에서 사용할 수 있을 뿐만 아니라 기본적으로 활성화됩니다.

코드 블록 내용을 클립보드에 복사

Just a little extra announcement to append to this… The setting has proved to be so useful and universally lauded that it is now not only default on but also tucked away as a hidden site setting: https://github.com/discourse/discourse/commit/81f3f56deb9d9f363e8b3bdcf81306fc34751d7d