Fix video url in next A first uniform

Author: eliemichel

basic-3d-rendering/shader-uniforms/a-first-uniform.md

@@ -587,7 +587,7 @@ We place this for instance at the beginning of `Application::MainLoop()`:
 
 <figure class="align-center">
 	<video autoplay loop muted inline nocontrols style="width:100%;height:auto;max-width:642px">
-		<source src="../../_static/turning-webgpu-logo.mp4" type="video/mp4">
+		<source src="../../../_static/turning-webgpu-logo.mp4" type="video/mp4">
 	</video>
 	<figcaption>
 		<p><span class="caption-text">Our first dynamic scene!</span></p>