Feature: iFrame widget (#2261)

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

docs/widgets/services/iframe.md

@@ -0,0 +1,35 @@
+---
+title: iFrame
+Description: Add a custom iFrame Widget
+---
+
+A basic iFrame widget to show external content, see the [MDN docs](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe) for more details about some of the options.
+
+!!! warning
+
+    Requests made via the iFrame widget are inherently **not proxied** as they are made from the browser itself.
+
+## Basic Example
+
+```yaml
+widget:
+  type: iframe
+  name: myIframe
+  src: http://example.com
+```
+
+## Full Example
+
+```yaml
+widget:
+  type: iframe
+  name: myIframe
+  src: http://example.com
+  classes: h-60 sm:h-60 md:h-60 lg:h-60 xl:h-60 2xl:h-72 # optional, use tailwind height classes, see https://tailwindcss.com/docs/height
+  referrerPolicy: same-origin # optional, no default
+  allowPolicy: autoplay fullscreen gamepad # optional, no default
+  allowFullscreen: false # optional, default: true
+  loadingStrategy: eager # optional, default: eager
+  allowScrolling: no # optional, default: yes
+  refreshInterval: 2000 # optional, no default
+```