**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
self.assertEqual(
            'search=%27%3E%22%2F%3E%3Cimg+src%3Dx+onerror%3Dalert%281%29%3E',
            utils.get_params(search="'>\"/><img src=x onerror=alert(1)>"),
        )
    def test_state_token(self):
        
        
        html = str(utils.state_token('<script>alert(1)</script>'))
        self.assertIn(
            '&lt;script&gt;alert(1)&lt;/script&gt;',
            html,
        )
        self.assertNotIn(
            '<script>alert(1)</script>',
            html,
        )
    def test_task_instance_link(self):
        from airflow.www.app import cached_app
        with cached_app(testing=True).test_request_context():
            html = str(
                utils.task_instance_link(
                    {'dag_id': '<a&1>', 'task_id': '<b2>', 'execution_date': datetime.now()}
                )
            )
        self.assertIn('%3Ca%261%3E', html)
        self.assertIn('%3Cb2%3E', html)
        self.assertNotIn('<a&1>', html)
        self.assertNotIn('<b2>', html)
    def test_dag_link(self):