Add Picture-in-Picture (PiP) Firefox limitation for OptiView Ads (#538)

Author: rbnbtns

ads/limitations/index.mdx

@@ -0,0 +1,15 @@
+---
+sidebar_position: 3
+sidebar_label: Limitations and known issues
+---
+
+# Limitations and known issues
+
+This page lists the current limitations and known issues of OptiView Ads.
+
+## Using OptiView Ads with Picture-in-Picture (PiP) on Firefox for Web
+
+Using OptiView Ads with Picture-in-Picture (PiP) on Firefox for Web is currently not supported. During playback, the default PiP button
+will be hidden to discourage usage.
+
+Note that users will still be able to trigger PiP using the button in the browser's address bar.

sidebarsAds.ts

@@ -25,6 +25,16 @@ const sidebars: SidebarsConfig = {
       link: { type: 'doc', id: 'how-to-guides/index' },
       items: [{ type: 'autogenerated', dirName: 'how-to-guides' }],
     },
+    {
+      type: 'category',
+      label: 'Limitations and known issues',
+      description: 'Take notice of the limitations and known issues when using OptiView Ads.',
+      customProps: {
+        icon: '⚠️',
+      },
+      link: { type: 'doc', id: 'limitations/index' },
+      items: [{ type: 'autogenerated', dirName: 'limitations' }],
+    },
     {
       type: 'category',
       label: 'API references',