[MultiAZ] How to use?

First of all thank you so much for doing https://github.com/aws/aws-parallelcluster/issues/3576

I've read the doc and the release notes and I've also looked at parts of the source of 3.4.0
I see validators on configuration using MultiAZ but I don't see how to set it up.

Am I right that `pcluster configure` doesn't propose/support it?
Does this mean we need to create our VPCs manually first THEN call `pcluster configure`

If there is doc, I missed it, could you share the link to it please.

Thank you!

Start by reviewing the MultiAZ documentation, release notes, and the 3.4.0 source referenced in the issue, then inspect how `pcluster configure` handles the setting. Document the supported setup and whether users must create VPCs manually first; done means the workflow is clear and linked from the relevant documentation.

Written by the indexing model from the issue text.