**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

airflow/www/utils.py
return page == current
    for page in pages:
        vals = {
            'is_active': 'active' if is_current(current_page, page) else '',
            'href_link': void_link
            if is_current(current_page, page)
            else '?{}'.format(get_params(page=page, search=search, status=status)),
            'page_num': page + 1,
        }
        output.append(page_node.format(**vals))  
    is_disabled = 'disabled' if current_page >= num_of_pages - 1 else ''
    page_link = (
        void_link
        if current_page >= num_of_pages - 1
        else '?{}'.format(get_params(page=current_page + 1, search=search, status=status))
    )
    output.append(next_node.format(href_link=page_link, disabled=is_disabled))  
    output.append(
        last_node.format(
            href_link="?{}".format(get_params(page=last_page, search=search, status=status)),  
            disabled=is_disabled,
        )
    )
    output.append(Markup('</ul>'))
    return Markup('\n'.join(output))
def epoch(dttm):