Previously the current version would always be unreleased at /docs/next
and we'd have to copy the doc/md/ folder into the
doc/website/versioned_docs/version-v1alpha5/ every time we made a
change.
We're going to be working on v1alpha5 for awhile so it makes sense to
just have the current version published at /docs/v1alpha5/ and we can
start /docs/v1alpha6/ whenever we're ready.
This also has the nice effect of giving us permalinks if we change the
structure again. /docs/v1alpha5/ will remain over time.