Update the documentation to add description of metered_account

Author: tabito-hara

website/docs/d/vpc_ipam.html.markdown

@@ -38,6 +38,7 @@ This data source exports the following attributes in addition to the arguments a
 * `enable_private_gua` - If private GUA is enabled.
 * `id` - ID of the IPAM resource.
 * `ipam_region` - Region that the IPAM exists in.
+* `metered_account` - AWS account that is charged for active IP addresses managed in IPAM.
 * `operating_regions` - Regions that the IPAM is configured to operate in.
 * `owner_id` - ID of the account that owns this IPAM.
 * `private_default_scope_id` - ID of the default private scope.

website/docs/r/vpc_ipam.html.markdown

@@ -63,6 +63,7 @@ This resource supports the following arguments:
 * `cascade` - (Optional) Enables you to quickly delete an IPAM, private scopes, pools in private scopes, and any allocations in the pools in private scopes.
 * `description` - (Optional) A description for the IPAM.
 * `enable_private_gua` - (Optional) Enable this option to use your own GUA ranges as private IPv6 addresses. Default: `false`.
+* `metered_account` - (Optional) AWS account that is charged for active IP addresses managed in IPAM. Valid values are `ipam-owner` (default) and `resource-owner`.
 * `operating_regions` - (Required) Determines which locales can be chosen when you create pools. Locale is the Region where you want to make an IPAM pool available for allocations. You can only create pools with locales that match the operating Regions of the IPAM. You can only create VPCs from a pool whose locale matches the VPC's Region. You specify a region using the [region_name](#operating_regions) parameter. You **must** set your provider block region as an operating_region.
 * `tier` - (Optional) specifies the IPAM tier. Valid options include `free` and `advanced`. Default is `advanced`.
 * `tags` - (Optional) A map of tags to assign to the resource. If configured with a provider [`default_tags` configuration block](https://registry.terraform.io/providers/hashicorp/aws/latest/docs#default_tags-configuration-block) present, tags with matching keys will overwrite those defined at the provider-level.