fix: correct comment unit from 500s to 500ms in Preview bundler listener

Author: cspatric

src/components/MDX/Sandpack/Preview.tsx

@@ -121,7 +121,7 @@ export function Preview({
           /**
            * The spinner component transition might be longer than
            * the bundler loading, so we only show the spinner if
-           * it takes more than 500s to load the bundler.
+           * it takes more than 500ms to load the bundler.
            */
           timeout = setTimeout(() => {
             setShowLoading(true);