docs: use coder modules in offline deployments (#11788)

* docs: use coder modules in offline deployments

* fix typos

* Update offline installation instructions with Artifactory support for Coder modules

* Review suggestions

docs/install/offline.md

@@ -230,6 +230,58 @@ server, as demonstrated in the example below:
 With these steps, you'll have the Coder documentation hosted on your server and
 accessible for your team to use.
 
+## Coder Modules
+
+### Artifactory
+
+Air gapped users can clone the [coder/modules](htpps://github.com/coder/modules)
+repo and publish a
+[local terraform module repository](https://jfrog.com/help/r/jfrog-artifactory-documentation/set-up-a-terraform-module/provider-registry)
+to resolve modules via [Artifactory](https://jfrog.com/artifactory/).
+
+1. Create a local-terraform-repository with name `coder-modules-local`
+2. Create a virtual repository with name `tf`
+3. Follow the below instructions to publish coder modules to Artifactory
+
+   ```shell
+   git clone https://github.com/coder/modules
+   cd modules
+   jf tfc
+   jf tf p --namespace="coder" --provider="coder" --tag="1.0.0"
+   ```
+
+4. Generate a token with access to the `tf` repo and set an `ENV` variable
+   `TF_TOKEN_example.jfrog.io="XXXXXXXXXXXXXXX"` on the Coder provisioner.
+5. Create a file `.terraformrc` with following content and mount at
+   `/home/coder/.terraformrc` within the Coder provisioner.
+
+   ```hcl
+   provider_installation {
+     direct {
+         exclude = ["registry.terraform.io/*/*"]
+     }
+     network_mirror {
+         url = "https://example.jfrog.io/artifactory/api/terraform/tf/providers/"
+     }
+   }
+   ```
+
+6. Update module source as,
+
+   ```hcl
+   module "module-name" {
+     source = "https://example.jfrog.io/tf__coder/module-name/coder"
+     version = "1.0.0"
+     agent_id = coder_agent.example.id
+     ...
+   }
+   ```
+
+> Do not forget to replace example.jgrog.io with uour Artifactory URL
+
+Based on the instructions
+[here](https://jfrog.com/blog/tour-terraform-registries-in-artifactory/).
+
 ## Firewall exceptions
 
 In restricted internet networks, Coder may require connection to internet.