Document how to use with Self-Hosted Pulumi Service

[clstokes]

Problem description

Should document how to use the operator with a Self-Hosted Pulumi Service - e.g. pulumi login https://api.pulumi.example.com.

[pgavlin]

@clstokes how important/urgent is this?

[clstokes]

This is solved with #106.

pulumi-kubernetes-operator/deploy/crds/pulumi.com_stacks.yaml

Lines 38 to 40 in bd45f50

	backend:
	description: (optional) Backend is an optional backend URL to use for all Pulumi operations.
	type: string

For example:

apiVersion: v1
kind: Secret
metadata:
  name: pulumi-api-secret
type: Opaque
stringData:
  accessToken: "<REDACTED: PULUMI_ACCESS_TOKEN>"
---
apiVersion: pulumi.com/v1alpha1
kind: Stack
metadata:
  name: nginx-k8s-stack
spec:
  accessTokenSecret: pulumi-api-secret
  backend: https://api.pulumi.example.com                           # <- this line
  stack: joeduffy/nginx/dev
  projectRepo: https://github.com/metral/pulumi-nginx
  commit: 2b0889718d3e63feeb6079ccd5e4488d8601e353
  destroyOnFinalize: true