build docs with newer nixos

See merge request !113

docs.nix used to use <nixpkgs> so maybe that was why

I was about to make a new repository and complicate CI shell scripts to check
it out in the right place at the right time ... but why?

update the localdev grid's secrets and other configuration to reflect this

testing and production are broken by this commit since they have not been
updated similarly

They're only example but they scare me when they show up in grep results

no reason to keep carrying out custom graphviz package or build all this old
junk just for the docs

Secure swap space and have 8 GB of swap consistently on all machines.

Closes privatestorageops#351

See merge request !103

Rationalize system host names

Closes #67

See merge request !110

There is no swap to use but (a) try the setting anyway and (b) maybe there
will be at some point.

See, it makes more sense.

we deleted it already but it got brought back

Regularize (somewhat) the definition of grids for Morph

See merge request !109

Also this no longer needs to be rec

It is no longer required to add IP addresses to the Vagrant-generated ssh
configuration because the Vagrant-configured hostnames now match up with the
names morph will try to use to connect to the VMs.

Just require hostName and domain instead of an extra publicIPv4 option.  Leave
behind a similar option, `publicAddress`, just in case it needs to be
overridden at some point, but stop supplying a value for it anywhere.