Update the changelog for a bug fixed in 1219dd2dcbd2b5c3081921f655fc926c6193c470 without being noticed.

Depending on how subtitle entries overlapped, two missing "break" statements could cause some subtitle entries to be added twice to the same segment and thus to be rendered twice. This leaded to incorrect transparency in the renderer subpicture.

Fixes #2460.
Update translations from Transifex:

 - Greek.