title: React-admin Array input with array of strings/numbers
body: <p><a href="https://marmelab.com/react-admin/Inputs.html#arrayinput" rel="noreferrer">https://marmelab.com/react-admin/Inputs.html#arrayinput</a>
  Examples cover cases where you have an array of objects:</p>
  
  <pre><code>  backlinks: [
          {
              date: '2012-08-10T00:00:00.000Z',
              url: 'http://example.com/foo/bar.html',
          },
          {
              date: '2012-08-14T00:00:00.000Z',
              url: 'https://blog.johndoe.com/2012/08/12/foobar.html',
          }
     ]
  </code></pre>
  
  <p>is it possible to have it work with just an array of strings?</p>
  
  <pre><code>backlinks: ['a', 'b', 'c']
  </code></pre>