Pass git configuration variables via terraform (#3034)

* Pass workspace owner email address to provisioner

* Remove owner_email and owner_username fields from agent metadata

* Add Git environment variables to example templates

* Remove "owner_name" field from provisioner metadata, use username instead

* Remove Git configuration from most templates, add documentation

* Proofreading/typo fixes from @mafredri

* Update example templates to latest version of terraform-provider-coder

docs/templates.md

@@ -42,7 +42,7 @@ code once you run `coder templates init` (new) or `coder templates pull`
 ## Concepts in templates
 
 While templates are written with standard Terraform, the
-[Coder Terraform Provider](https://registry.terraform.io/providers/coder/coder/latest/docs) is 
+[Coder Terraform Provider](https://registry.terraform.io/providers/coder/coder/latest/docs) is
 used to define the workspace lifecycle and establish a connection from resources
 to Coder.
 
@@ -51,7 +51,7 @@ template options, reference [Coder Terraform provider docs](https://registry.ter
 
 ### Resource
 
-Resources in Coder are simply [Terraform resources](https://www.terraform.io/language/resources). 
+Resources in Coder are simply [Terraform resources](https://www.terraform.io/language/resources).
 If a Coder agent is attached to a resource, users can connect directly to the resource over
 SSH or web apps.
 
@@ -60,12 +60,12 @@ SSH or web apps.
 Once a Coder workspace is created, the Coder agent establishes a connection
 between a resource (docker_container) and Coder, so that a user can connect to
 their workspace from the web UI or CLI. A template can have multiple agents to
-allow users to connect to multiple resources in their workspace. 
+allow users to connect to multiple resources in their workspace.
 
 > Resources must download and start the Coder agent binary to connect to Coder.
 > This means the resource must be able to reach your Coder URL.
 
-Use the Coder agent's init script to 
+Use the Coder agent's init script to
 
 ```hcl
 data "coder_workspace" "me" {
@@ -90,6 +90,11 @@ resource "kubernetes_pod" "pod1" {
 }
 ```
 
+The `coder_agent` resource can be configured as described in the
+[documentation for the `coder` Terraform provider.](https://registry.terraform.io/providers/coder/coder/latest/docs/resources/agent)
+For example, you can use the `env` property to set environment variables that will be
+inherited by all child processes of the agent, including SSH sessions.
+
 ### Parameters
 
 Templates often contain _parameters_. These are defined by `variable` blocks in
@@ -202,6 +207,31 @@ By default, all templates allow developers to connect over SSH and a web
 terminal. See [Configuring Web IDEs](./ides/configuring-web-ides.md) to
 learn how to give users access to additional web applications.
 
+### Data source
+
+When a workspace is being started or stopped, the `coder_workspace` data source provides
+some useful parameters. See the [documentation for the `coder` Terraform provider](https://registry.terraform.io/providers/coder/coder/latest/docs/data-sources/workspace)
+for more information.
+
+For example, the [Docker quick-start template](https://github.com/coder/coder/tree/main/examples/templates/docker)
+sets a few environment variables based on the username and email address of the workspace's owner, so
+that you can make Git commits immediately without any manual configuration:
+
+```tf
+resource "coder_agent" "dev" {
+  # ...
+  env = {
+    GIT_AUTHOR_NAME = "${data.coder_workspace.me.owner}"
+    GIT_COMMITTER_NAME = "${data.coder_workspace.me.owner}"
+    GIT_AUTHOR_EMAIL = "${data.coder_workspace.me.owner_email}"
+    GIT_COMMITTER_EMAIL = "${data.coder_workspace.me.owner_email}"
+  }
+}
+```
+
+You can add these environment variable definitions to your own templates, or customize them however
+you like.
+
 ## Creating & troubleshooting templates
 
 You can use any Terraform resources or modules with Coder! When working on