Add "import" example section to all resources in the documentation

[snke23]

In the documentation of other providers, you can usually find an import section of the resource, e.g. https://registry.terraform.io/providers/terraform-provider-openstack/openstack/latest/docs/resources/images_image_v2#import

Can we have that for the STACKIT terraform provider documentation, too?

If I want to import a STACKIT resource, I either look at the code, or let the error message show me what is required: fmt.Sprintf("Expected import identifier with format: [project_id],[image_id] Got: %q", req.ID),

[Fyusel]

Hi @snke23,
thank you for reporting this. This is a good way to further improve our documentation we will add this 👍