Update gitbook to 0.5.6
Update gitbook to 0.5.6

Futuring/editor-legacy,Futuring/editor-legacy,zhanghuiguoanlige/editor-legacy,KINGSABRI/editor-legacy,KINGSABRI/editor-legacy,gdbooks/editor-legacy,GitbookIO/editor-legacy,GitbookIO/editor-legacy,gdbooks/editor-legacy,zhanghuiguoanlige/editor-legacy,Futuring/editor-legacy,KINGSABRI/editor-legacy,GitbookIO/editor-legacy,gdbooks/editor-legacy,zhanghuiguoanlige/editor-legacy