Co-authored-by: native-api <vano@mail.mipt.ru>

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>

The text included info on Pyenv startup which is now outdated and incorrect.

Closes https://github.com/pyenv/pyenv/issues/1947, https://github.com/pyenv/pyenv-virtualenv/issues/387

Otherwise, there's no effect for non-login interactive shells

`psub` here is entirely unnecessary.

-Replace Mac OS X with macOS
-Added links

When I came back to this after a few months - despite setting it up properly previously - I was a bit confused since I'm so used to setting an actual Python version in `.python-version` files. Explain exactly how the file should look.

Both directories need to be deleted or a subsequent install with the same name will fail

pyenv install 3.4.3 my-virtual-env:
rm -rf ~/.pyenv/versions/my-virtual-env ~/.pyenv/versions/3.4.3/my-virtual-env

This fixes issue: https://github.com/yyuu/pyenv-virtualenv/issues/36

It will be done by `get-pip.py` and we don't have to do anything explicitly.

First release after my son's birth....

Currently the link to venv points to the Japanese version of the Python documentation.
Change this link to the English version of the Python documentation.

It is necessary only if user want automatic fashion of activation.
If the users of pyenv-virtualenv doesn't need the feature, they can
omit the configuration safely.