Prefer readthedocs.io instead of readthedocs.org for doc links
Prefer readthedocs.io instead of readthedocs.org for doc links

Read the Docs moved hosting to readthedocs.io instead of readthedocs.org. Fix
all links in the project.

For additional details, see:

https://blog.readthedocs.com/securing-subdomains/

> Starting today, Read the Docs will start hosting projects from subdomains on
> the domain readthedocs.io, instead of on readthedocs.org. This change
> addresses some security concerns around site cookies while hosting user
> generated data on the same domain as our dashboard.

sigmavirus24/urllib3,sigmavirus24/urllib3,urllib3/urllib3,urllib3/urllib3