Ignore `for_each` blocks coming from the Terraform Provider documentation

### What problem are you facing?

Some resources in the Terraform docs have a `for_each` block in the Example Usage - For example [aws_autoscaling_group_tag](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscaling_group_tag#example-usage). These blocks end up being parsed in the `examples-generated` directory of the resulting Crossplane Provider - [Example in provider-aws](https://github.com/upbound/provider-aws/blob/0f0d7a43d9d3b4919fb0f708f3a4794081dfbdd8/examples-generated/autoscaling/grouptag.yaml#L14)

### How could Upjet help solve your problem?

When parsing [provider-metadata.yaml](https://github.com/upbound/provider-aws/blob/v0.40.0/config/provider-metadata.yaml) (Example from line 8023), it would be useful to skip the `for_each` keys from the `examples.manifest` block so that they don't end up as YAML examples