**Apache Airflow version**: 1.10.11

**Environment**: Python 3.7

- **Cloud provider or hardware configuration**:
- **OS** (e.g. from /etc/os-release): PRETTY_NAME="Debian GNU/Linux 10 (buster)"
 (from python3.7-slim-buster docker image)
- **Kernel** (e.g. `uname -a`): Linux 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 GNU/Linux
- **Install tools**:
- **Others**:

**What happened**:

Using a markdown formatted table does not work.

**What you expected to happen**:

To be able to see a formated table within DAG view

**How to reproduce it**:

Add a tabular formatted code do dag.doc_md.

Example:

> mytable:
> 
> | a | b | c |
> | ------------- | ------------- | ------------- |
> | a | b | c |

[Table not formatted](https://i.imgur.com/l6JXuWe.png)

**Anything else we need to know**: N/A

tests/www/test_utils.py
extra_links = 4  
        search = "'>\"/><img src=x onerror=alert(1)>"
        html_str = utils.generate_pages(current_page, total_pages, search=search)
        self.assertNotIn(search, html_str, "The raw search string shouldn't appear in the output")
        self.assertIn('search=%27%3E%22%2F%3E%3Cimg+src%3Dx+onerror%3Dalert%281%29%3E', html_str)
        self.assertTrue(callable(html_str.__html__), "Should return something that is HTML-escaping aware")
        dom = BeautifulSoup(html_str, 'html.parser')
        self.assertIsNotNone(dom)
        ulist = dom.ul
        ulist_items = ulist.find_all('li')
        self.assertEqual(min(window, total_pages) + extra_links, len(ulist_items))
        page_items = ulist_items[2:-2]
        mid = int(len(page_items) / 2)
        for i, item in enumerate(page_items):
            a_node = item.a
            href_link = a_node['href']
            node_text = a_node.string
            if node_text == str(current_page + 1):
                if check_middle:
                    self.assertEqual(mid, i)
                self.assertEqual('javascript:void(0)', href_link)
                self.assertIn('active', item['class'])
            else:
                self.assertRegex(href_link, r'^\?', 'Link is page-relative')
                query = parse_qs(href_link[1:])
                self.assertListEqual(query['page'], [str(int(node_text) - 1)])
                self.assertListEqual(query['search'], [search])
    def test_generate_pager_current_start(self):