Improve the documentation on the Support of StackGres on AKS

We need to make more clear in our documentation that we support AKS.

A customer comment:

There are AKS references here https://stackgres.io/doc/1.1/demo/quickstart/ and here https://stackgres.io/doc/latest/quickstart/
but it is not listed here https://stackgres.io/doc/latest/install/prerequisites/k8s/.

Acceptance criteria:

• Fix the documentation