add silver sponsor

Author: yngrtc

index.html

@@ -166,6 +166,11 @@
             target="_blank">Try the interactive Chat tutorial</a> 💬
         </p>
         <br>
+        <p>
+            <a href="https://kittycad.io/" target="_blank">
+            <img src="https://raw.githubusercontent.com/webrtc-rs/webrtc/master/doc/KittyCAD.png" alt="KittyCAD"></a>
+        </p>
+        <br>
         <p>
           <strong>IDE Sponsored by JetBrains:</strong><br><br>
           <a href="https://www.jetbrains.com/go/?from=WebRTC.rs"    target="_blank"><img src="./res/goland.png" alt="GoLand"></a>