Updating GitLab Pages Setup post to match the new GitLab UI

Updates:

• Project's settings => now menu is on the top
• Screenshots => with new menu
• Notes => {: .notes} instead of >
• ToC => {:toc} instead of descriptive toc
• Custom ids => {: #id} instead of html anchor
• Removed extra blank spaces at the end of each line

Post: https://about.gitlab.com/2016/04/07/gitlab-pages-setup/