fix typo in the href of a link to papers page (/uist2016/posters -> /uist2016/papers) in home
fix typo in the href of a link to papers page (/uist2016/posters -> /uist2016/papers) in home

ryosuzuki/UIST-2016,ryosuzuki/UIST-2016,ryosuzuki/UIST-2016,ryosuzuki/UIST-2016