chores: update theme logo

Author: tstreamDOTh

.storybook/customtheme.js

@@ -3,6 +3,6 @@ import { create } from "@storybook/theming";
 export default create({
     base: "light",
     brandTitle: "typhoon-ui",
-    brandUrl: "https://typhoon-ui.dgraph.io",
-    brandImage: `https://github.com/dgraph-io/typhoon-ui`,
+    brandUrl: "https://github.com/dgraph-io/typhoon-ui",
+    brandImage: `https://user-images.githubusercontent.com/11137394/130053143-498c0d26-0111-479c-a99c-31b82968ac1d.png`,
 });