docs(scripting): add custom converter video (#586)

<img width="2566" height="1894" alt="CleanShot 2026-03-30 at 15 11
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src="https://github.com/user-attachments/assets/45950ce6-292d-4748-9654-beb6d5b55c2e"
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Author: lancesnider

scripting/protocols/converter-scripts.mdx

@@ -4,12 +4,15 @@ description: "Create custom converters using Rive scripting"
 ---
 
 import { Demos } from '/snippets/demos.jsx'
+import { YouTube } from '/snippets/youtube.mdx'
 
 Rive includes several built-in converters like **Convert to String** and **Round**.
 Scripting lets you create your own custom converters when you need behavior that isn’t covered by the built-ins.
 
 For background on converters and data binding, see [Data Converters](/editor/data-binding/overview#converter).
 
+<YouTube id="rPIEATBt4Qo" />
+
 ## Examples
 
 <Demos