Changelog: mention another bugfix in 2.17
Changelog: mention another bugfix in 2.17

@dennisschagt noticed that 2.17 fixed another issue that weren't closed
and/or mentioned in the changelog:
https://github.com/newsboat/newsboat/issues/473#issuecomment-720122957

der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat