Update pages to put previous/next in front matter

After V2 goes live, the following pages need to be updated to put links to previous and next pages in front matter instead of panels.

• https://doc.nuxeo.com/nxdoc/getting-started-with-the-nuxeo-platform/ and children
• https://doc.nuxeo.com/nxdoc/first-steps-with-studio-technical-documentation-tutorial/ and children

Add them to tutorials with several pages.
Check on static branch as well.