airflow 1.7.3 incompatibility notice on website

[Jayesh Senjaliya <jh...@gmail.com>]

Hi Guys,

since airflow 1.7.3 has some compatibility issues regarding Jinja2 (2.9.2),
its been breaking for lot of people around the world.

so we came up with suggestion to put up the notice on website about this
version and also note on how to fix it ( most likely only downgrading to
Jinja2 2.8.1 is required )

it would be great if someone can do this sooner than later. here is the
ticket:
AIRFLOW-744 <https://issues.apache.org/jira/browse/AIRFLOW-744>

Here is the short conversation about it for more context. ( copy/pasted
from gitter )
Jerzy J. Gangi @jerzygangi 12:14
I'm just imagining a lot of people around the world installing airflow
yesterday and today, and it's not working...

bolkedebruin @bolkedebruin 12:15
I understand that, be we can't fix it. Under the apache brand we cannot do
another release of 1.7.1.X
1.8 will be out quite soon

Jayesh @jhsenjaliya 12:15
can we put notification on website ?

bolkedebruin @bolkedebruin 12:16
we can, please suggest it on the mailinglist so someone can pick that up
good idea