def generate_redirect_from(doc)
      doc.redirect_from.each do |path|
        page = RedirectPage.redirect_from(doc, path)
        doc.site.pages << page
        redirects[page.redirect_from] = page.redirect_to
      end
    end
def generate_redirect_from(doc)
      doc.redirect_from.each do |path|
        page = RedirectPage.redirect_from(doc, path)
        doc.site.pages << page
        redirects[page.redirect_from] = page.redirect_to
      end
    end
For every `redirect_from` entry, generate a redirect page