Website: Add map example to templatefile function docs (#26126)

This change adds an example of using a map with a few keys and shows how it runs it.

Co-authored-by: Nick Fagerlund <nick@hashicorp.com>

website/docs/configuration/functions/templatefile.html.md

@@ -49,6 +49,8 @@ to render templates while respecting resource dependencies.
 
 ## Examples
 
+### Lists
+
 Given a template file `backends.tmpl` with the following content:
 
 ```
@@ -66,6 +68,34 @@ backend 10.0.0.2:8080
 
 ```
 
+### Maps
+
+Given a template file `config.tmpl` with the following content:
+
+```
+%{ for config_key, config_value in config }
+set ${config_key} = ${config_value}
+%{ endfor ~}
+```
+
+The `templatefile` function renders the template:
+
+```
+> templatefile(
+               "${path.module}/backends.tmpl", 
+               { 
+                 config = {
+                   "x"   = "y"
+                   "foo" = "bar"
+                   "key" = "value"
+                 }
+               }
+              )
+set foo = bar
+set key = value
+set x = y
+```
+
 ### Generating JSON or YAML from a template
 
 If the string you want to generate will be in JSON or YAML syntax, it's