Update registry_module.html.markdown

[amarrone-hashicorp]

Add in sentence about expected naming pattern for vcs{} block in generic VCS repos.

Description

After attempting to use the tfe provider to populate an HCP terraform PMR with some VCS backed modules I noticed that the naming convention of the VCS backed repo has to follow the terraform-PROVIDER-NAME pattern for modules in the public registry.

This is not documented in the provider documentation. Adding it to help others avoid the frustration I experienced.

For example the following code will not work:

resource "tfe_registry_module" "key_pair" {
  organization    = var.organization
  name            = "key-pair"
  vcs_repo {
    display_identifier = "root/key-pair"
    identifier         = "root/key-pair"
    oauth_token_id     = tfe_oauth_client.gitlab.oauth_token_id
  }
}

The display_identifier and identifier attributes need to follow the public module registry naming convention as shown below.

This is the expected naming convention that will allow the VCS connection to work:

resource "tfe_registry_module" "key_pair" {
  organization    = var.organization
  name            = "key-pair"
  vcs_repo {
    display_identifier = "root/terraform-aws-key-pair"
    identifier         = "root/terraform-aws-key-pair"
    oauth_token_id     = tfe_oauth_client.gitlab.oauth_token_id
    branch             = "main"
  }
}

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