Update screenshots for Calligra sheets 3.1
Summary: Update screenshots for Calligra sheets 3.1 also reflect change in a menu name. Only the hidencells screenshots aren't updated. I wasn't able to reproduce the steps.
Test Plan: checkXML5 index.dockbook
Reviewers: #calligra:_3.0, Documentation, yurchor
Reviewed By: Documentation, yurchor
Subscribers: yurchor, leinir, Calligra-Devel-list, kde-doc-english
Tags: #calligra:_3.0, Documentation
Differential Revision: https://phabricator.kde.org/D18994