Update docs for ASG wait for capacity with ALBs
Update docs for ASG wait for capacity with ALBs

This updates the docs for ASG to note that wait for capacity can now be
used for ALBs attached via `target_group_arns` not just ELBs attached
via `load_balancers` (see Terraform issue
https://github.com/hashicorp/terraform/issues/8655 and PR
https://github.com/hashicorp/terraform/pull/10243 for the change to make
this work for ALBs).

Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,kjmkznr/terraform-provider-aws,Ninir/terraform-provider-aws,nbaztec/terraform-provider-aws,kjmkznr/terraform-provider-aws,nbaztec/terraform-provider-aws,Ninir/terraform-provider-aws,kjmkznr/terraform-provider-aws,Ninir/terraform-provider-aws,terraform-providers/terraform-provider-aws,nbaztec/terraform-provider-aws,nbaztec/terraform-provider-aws,kjmkznr/terraform-provider-aws,terraform-providers/terraform-provider-aws,terraform-providers/terraform-provider-aws