**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
"""Generates a URL to the Graph View for a Dag."""
    dag_id = attr.get('dag_id')
    execution_date = attr.get('execution_date')
    url = url_for('Airflow.graph', dag_id=dag_id, execution_date=execution_date)
    return Markup('<a href="{}">{}</a>').format(url, dag_id) if dag_id else Markup('None')  
def dag_run_link(attr):
    """Generates a URL to the Graph View for a DagRun."""
    dag_id = attr.get('dag_id')
    run_id = attr.get('run_id')
    execution_date = attr.get('execution_date')
    url = url_for('Airflow.graph', dag_id=dag_id, run_id=run_id, execution_date=execution_date)
    return Markup('<a href="{url}">{run_id}</a>').format(url=url, run_id=run_id)  
def pygment_html_render(s, lexer=lexers.TextLexer):  
    """Highlight text using a given Lexer"""
    return highlight(s, lexer(), HtmlFormatter(linenos=True))
def render(obj, lexer):
    """Render a given Python object with a given Pygments lexer"""
    out = ""
    if isinstance(obj, str):
        out = Markup(pygment_html_render(obj, lexer))
    elif isinstance(obj, (tuple, list)):
        for i, text_to_render in enumerate(obj):
            out += Markup("<div>List item #{}</div>").format(i)  
            out += Markup("<div>" + pygment_html_render(text_to_render, lexer) + "</div>")
    elif isinstance(obj, dict):
        for k, v in obj.items():
            out += Markup('<div>Dict item "{}"</div>').format(k)  
            out += Markup("<div>" + pygment_html_render(v, lexer) + "</div>")
    return out
def wrapped_markdown(s, css_class=None):