[docs] Several typos in Python 3.7 docs.

[Zachary Ware]

On Fri, Sep 14, 2018 at 10:40 AM Никита Люшненко <zoodss at yandex.ru> wrote:
> Yes, it opens this link, and for some reason Firefox says that there is a "Problem loading page Unable to connect", and "The site could be temporarily unavailable or too busy. Try again in a few moments." And this message i got several times in the past months when i was trying to join list. And the same problem for any link, containing "mail.Python.org". I can see it trying, but nope.

Ah, that is unfortunate.  We have had reports from other Russians
about intermittent problems with connecting to our sites, likely due
to issues beyond our control.  However, you should also be able to
subscribe by sending a message to `<list-name>-join at python.org`, for
example, `core-mentorship-join at python.org`.

-- 
Zach