docs: better explain persistent resources (#4703)

docs/templates.md

@@ -164,13 +164,10 @@ resource "docker_image" "workspace" {
 }
 ```
 
-### Persistent vs. ephemeral resources
-
-You can use the workspace state to ensure some resources in Coder are
-persistent, while others are ephemeral.
-
 #### Start/stop
 
+[Learn about resource persistence in Coder](./templates/resource-persistence.md)
+
 Coder workspaces can be started/stopped. This is often used to save on cloud costs or enforce
 ephemeral workflows. When a workspace is started or stopped, the Coder server
 runs an additional
@@ -180,7 +177,7 @@ Coder provider that the workspace has a new transition state.
 This template sample has one persistent resource (docker volume) and one ephemeral resource
 (docker image).
 
-```sh
+```hcl
 data "coder_workspace" "me" {
 }