fix typo

Summary:
’ (U+2019 aka RIGHT SINGLE QUOTATION MARK)
is not
' (U+0027 aka APOSTROPHE)

it's U+0027 in "it's" :)

Reviewers: apol, mart

Reviewed By: mart

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D6110