Add YAML naming/case guidelines to style guide

[plumbis]

What's Missing?

The docs style guide should add content on proper styling for Kubernetes YAML definitions likekinds and names.

The Kube docs is a good starting point https://kubernetes.io/docs/contribute/style/style-guide/#documentation-formatting-standards

This was called out in f821153 (#326)

[negz]

I think there's almost two things here:

• A style guide for writing things like CompositeResourceDefinition outside of example manifests.
• What is valid and idiomatic inside example manifests.

I like that Kubernetes style guide for the former. There's also a lot of Crossplane-specific advice on style in https://docs.crossplane.io/v1.11/concepts/terminology/.