We have a collision in Sphinx since we defined the link "_controller" twice, so currently it is a circular reference:
http://docs.deis.io/en/latest/gettingstarted/architecture/?highlight=controller#controller

It appears to me we mean to refer to this:
http://docs.deis.io/en/latest/components/controller/
when we reference a canonical "controller" link within the docs, so renaming this one to "_arch_controller" seems to fix things.