broken examples links in readme

[abuxton]

4 of the links under https://github.com/hashicorp/terraform-google-terraform-enterprise#examples are broken

[Standalone](https://github.com/hashicorp/terraform-google-terraform-enterprise/blob/main/examples/standalone)
[Active/Active](https://github.com/hashicorp/terraform-google-terraform-enterprise/blob/main/examples/active-active)
[Existing Network](https://github.com/hashicorp/terraform-google-terraform-enterprise/blob/main/examples/existing-network)
[Outbound Proxy](https://github.com/hashicorp/terraform-google-terraform-enterprise/blob/main/examples/proxy)
[SharedVPC](https://github.com/hashicorp/terraform-google-terraform-enterprise/blob/main/examples/shared-vpc)

the examples folder contains 6 examples not 5 https://github.com/hashicorp/terraform-google-terraform-enterprise/tree/main/examples

it's not immediately obvious which link should now go to which link to provide a quick pull request.