DBSnapshot and DBClusterSnapshot are not documented

[vmercierfr]

What is the URL of the document?

https://aws-controllers-k8s.github.io/community/reference/rds/v1alpha1/dbinstance/

Which section(s) is the issue in?

The list of RDS resources

What needs fixing?

The following resources are missing from the documentation:

• DBSnapshot introduced in Generate DBSnpashot resource rds-controller#181
• DBClusterSnapshot introduced in Generate DBClusterSnapshot resource rds-controller#182

Additional context

We wanted to use the DBSnapshot resource but couldn't find any documentation.

Meanwhile, we are looking at the Kubernetes Custom Resource definition in https://github.com/a-hilaly/ack-rds-controller/blob/release-v1.4.0/helm/crds/rds.services.k8s.aws_dbsnapshots.yaml

[vmercierfr]

cc @a-hilaly

[a-hilaly]

@vmercierfr our prow jobs for publishing doucmentation are currently broken, we have someone working on a fix :) https://prow.ack.aws.dev/view/s3/ack-prow-logs/logs/docs-release/1805447279469924352 - i'll ping here once their online