Document adoption-fields annotation values for resources #2763
Description
https://aws-controllers-k8s.github.io/docs/api-reference
ALL/MOST Resources
For 99% of ACK resources there exists no documentation on what should exist in the annotation services.k8s.aws/adoption-fields.
This would be understandable if adoption fields were either ARN (or name for resources without an ARN).
One place I have seen an attempt is ec2/VPC, however it simply just says $ADOPTION_FIELDS under the example.
It is currently a trial and error process to adopt resources into ACK, since each resource seems to use different adoption fields. (e.g. VPC used vpcID vs. Subnet uses subnetID)
I would recommend following the pattern of the VPC resource, however not simply saying $ADOPTION_FIELDS as the annotation values, but rather actually providing a minimal example. (e.g. services.k8s.aws/adoption-fields: { "vpcID": "vpc-000000000000000" })