closes #219, fixed default branch name in links

Author: himorin

webgpu/index.html

@@ -193,7 +193,7 @@ <h2 class='tagline'>WebGPU Sample Pages</h2>
             links.classList.add('links');
 
             let sourceLink = document.createElement('a');
-            sourceLink.href = 'https://github.com/immersive-web/webxr-samples/blob/master/' + page.path;
+            sourceLink.href = 'https://github.com/immersive-web/webxr-samples/blob/main' + page.path;
             sourceLink.textContent = 'Source';
             links.appendChild(sourceLink);
 
@@ -213,7 +213,7 @@ <h2 class='tagline'>WebGPU Sample Pages</h2>
 
       <p>Models used in these samples come from <a href="https://poly.google.com">Poly</a>, and many were modeled in <a href="https://vr.google.com/blocks/">Blocks</a>.<br/>
       They are stored and loaded using the <a href="https://www.khronos.org/gltf/">glTF 2.0 format</a>.<br/>
-      Attribution for individual models can be found under the <a href="https://github.com/immersive-web/webxr-samples/tree/master/media/gltf">media/gltf</a> folders for this repository.</p>
+      Attribution for individual models can be found under the <a href="https://github.com/immersive-web/webxr-samples/tree/main/media/gltf">media/gltf</a> folders for this repository.</p>
 
       <h3><a class='github-link' href='https://github.com/immersive-web/webxr-samples'>View samples source on GitHub</a></h3>