Update iframe.markdown

Minor cleanup and fixing typos
Changed all config sections to use {% configuration %} tag.

source/_lovelace/iframe.markdown

@@ -10,8 +10,6 @@ sharing: true
 footer: true
 ---
 
-### Iframe
-
 Iframe cards are useful to embed outside websites in your dashboard with little effort. One such example is a grafana view. You can also embed files stored in your `config/www` folder and reference them using `/local/<file>`.
 
 <p class='img'>
@@ -21,16 +19,30 @@ Screenshot of the iframe card.
 
 > Make sure the URL you're embedding has the right protocol and allows to be embedded in an iframe on a different domain. For example if your Home Assistant setup uses https you won't be able to embed http URLs
 
-**Options**
+{% linkable_title Options %}
 
-| Name | Type | Default | Description
-| ---- | ---- | ------- | -----------
-| type | string | **Required** | `iframe`
-| url | string | **Required** | iframe source url
-| aspect_ratio | string | `"50%"` | Iframe height-width-ratio
-| title | string | Optional | Card title
+{% configuration %}
+type:
+  required: true
+  description: iframe
+  type: string
+url:
+  required: true
+  description: iframe source url
+  type: string
+aspect_ratio:
+  required: false
+  description: Iframe height-width-ratio
+  type: string
+  default: "50%"
+title:
+  required: false
+  description: Card title
+  type: string
+  default: none
+{% endconfiguration %}
 
-**Examples**
+{% linkable_title Examples %}
 
 ```yaml
       - type: iframe