**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
"""Returns an epoch-type date (tuple with no timezone)"""
    return (int(time.mktime(dttm.timetuple())) * 1000,)
def json_response(obj):
    """Returns a json response from a json serializable python object"""
    return Response(
        response=json.dumps(obj, indent=4, cls=AirflowJsonEncoder), status=200, mimetype="application/json"
    )
def make_cache_key(*args, **kwargs):
    """Used by cache to get a unique key per URL"""
    path = request.path
    args = str(hash(frozenset(request.args.items())))
    return (path + args).encode('ascii', 'ignore')
def task_instance_link(attr):