Fix stylesheet toggle

Use rel attributes to specify currently selected theme.

packages/react-common-docs/src/components/ThemeToggle/ThemeToggle.tsx

@@ -26,8 +26,10 @@ const applyStyles = (theme) => {
   stylesheets.forEach(s => {
     const enabled = s.title === theme
     if (enabled) {
+      s.setAttribute('rel', 'stylesheet')
       s.removeAttribute('disabled')
     } else {
+      s.setAttribute('rel', 'alternate')
       s.setAttribute('disabled', 'disabled')
     }
   })