Merge pull request #9281 from nwalke/issue_9037

DOCS: Update interpolation page to show list usage

website/source/docs/configuration/interpolation.html.md

@@ -23,12 +23,17 @@ will be rendered as a literal `${foo}`.
 
 ## Available Variables
 
-**To reference user variables**, use the `var.` prefix followed by the
+**To reference user string variables**, use the `var.` prefix followed by the
 variable name. For example, `${var.foo}` will interpolate the
-`foo` variable value. If the variable is a map, then you
-can reference static keys in the map with the syntax
-`var.MAP["KEY"]`. For example, `${var.amis["us-east-1"]` would
-get the value of the `us-east-1` key within the `amis` map variable.
+`foo` variable value.
+
+**To reference user map variables**, the syntax is `var.MAP["KEY"]`.  For
+example, `${var.amis["us-east-1"]}` would get the value of the `us-east-1`
+key within the `amis` map variable.
+
+**To reference user list variables**, the syntax is `["${var.LIST}"]`.  For
+example, `["${var.subnets}"]` would get the value of the `subnets` list, as a
+list.
 
 **To reference attributes of your own resource**, the syntax is
 `self.ATTRIBUTE`. For example `${self.private_ip_address}` will

website/source/docs/configuration/variables.html.md

@@ -109,7 +109,7 @@ variable "users" {
 }
 ```
 
-The usage of maps, list, strings, etc. is documented fully in the
+The usage of maps, lists, strings, etc. is documented fully in the
 [interpolation syntax](/docs/configuration/interpolation.html)
 page.
 
@@ -194,7 +194,7 @@ $ TF_VAR_somemap='{foo = "bar", baz = "qux"}' terraform plan
 
 <a id="variable-files"></a>
 
-Variables can be collected in files and passed all at once using the 
+Variables can be collected in files and passed all at once using the
 `-var-file=foo.tfvars` flag. The format for variables in `.tfvars`
 files is [HCL](/docs/configuration/syntax.html#HCL), with top level key/value
 pairs: