docs: remove detail on default value for http_tokens (#38971)

website/docs/r/instance.html.markdown

@@ -369,7 +369,7 @@ The `metadata_options` block supports the following:
 * `http_endpoint` - (Optional) Whether the metadata service is available. Valid values include `enabled` or `disabled`. Defaults to `enabled`.
 * `http_protocol_ipv6` - (Optional) Whether the IPv6 endpoint for the instance metadata service is enabled. Defaults to `disabled`.
 * `http_put_response_hop_limit` - (Optional) Desired HTTP PUT response hop limit for instance metadata requests. The larger the number, the further instance metadata requests can travel. Valid values are integer from `1` to `64`. Defaults to `1`.
-* `http_tokens` - (Optional) Whether or not the metadata service requires session tokens, also referred to as _Instance Metadata Service Version 2 (IMDSv2)_. Valid values include `optional` or `required`. Defaults to `optional`.
+* `http_tokens` - (Optional) Whether or not the metadata service requires session tokens, also referred to as _Instance Metadata Service Version 2 (IMDSv2)_. Valid values include `optional` or `required`.
 * `instance_metadata_tags` - (Optional) Enables or disables access to instance tags from the instance metadata service. Valid values include `enabled` or `disabled`. Defaults to `disabled`.
 
 For more information, see the documentation on the [Instance Metadata Service](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html).