As per [their blog post of the 27th April](https://blog.readthedocs.com/securing-subdomains/) ‘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.
Test Plan: Manually visited all the links I’ve modified.
Fix the display of code samples in the Mathjax example doc, and squash
some warnings when building the docs.
This still doesn't make most of the examples display, because pandoc
makes the \begin{} & \end{} block into a raw latex block, which isn't
rendered in the HTML output. Not sure what to do about that.
Adam Chainz
Carol Willing
Matthias Geier
Min RK
Thomas Kluyver
Scott Sanderson
Jonathan Frederic
Matthias Bussonnier
stuntgoat