title: Sorting GraphQL query on multiple queries in Gatsby
body: <p>I'm using Gatsby as my static generator and Contentful as my datasource.</p>
  
  <p>We've got multiple contentTypes in Contentful (blog, event, whitepaper) and I want to return these in within one query and sorted by createdAt date. So far I have the following which returns each contentType in order of each contentType but not in order of date overall.</p>
  
  <p>Is there a way I can do a sort across the entire query?</p>
  
  <pre><code>{
      whitepapers: allContentfulWhitepaper(sort: { order: DESC, fields: createdAt }) {
        edges {
          node {
            id
            slug
            title
          }
        }
      }
      blogs: allContentfulBlogPost(sort: { order: DESC, fields: createdAt }) {
        edges {
          node {
            id
            slug
            title
          }
        }
      }
      events: allContentfulEventPage(sort: { order: DESC, fields: createdAt }) {
        edges {
          node {
            id
            slug
            title
          }
        }
      }
    }
  </code></pre>