Document how to add separate trusted-host values in the pip config.

[stonecharioteer]

It is not entirely obvious how to add multiple hosts to the trusted-hosts section of the config file. In an enterprise, it becomes important to trust pypi.org and an internal host providing a PYPI registry such as that provided by Jfrog Artifactory.

An appropriate section for this would be in the user-guide.

It already contains an example detailing how to add multiple URLs to find-links like so:

[global]
find-links =
    http://download.example.com

[install]
find-links =
    http://mirror1.example.com
    http://mirror2.example.com

However, the way trusted-host is named suggests that only one host can be trusted at any point of time. This is not true since the CLI can be used as:

pip install --trusted-host pypi.org --trusted-host artifactory.mydomain.com virtualenv

That would suggest to an experienced user that:

[install]
trusted-host = 
    https://pypi.org
    https://artifactory.mydomain.com

Furthermore, searching for this option points to this SO question and answer..

Newer users would benefit from having this documented clearly somewhere, since people struggle with using pip in an enterprise situation where SSL errors are a dime a dozen.