Updated Giscus example to support theme change without reload

docs/setup/adding-a-comment-system.md

@@ -74,7 +74,17 @@ calling the `super()` function at the beginning of the block:
     document.addEventListener("DOMContentLoaded", function() {
       var ref = document.querySelector("[data-md-component=palette]")
       ref.addEventListener("change", function() {
-        location.reload()
+        var palette = __md_get("__palette")
+        if (palette && typeof palette.color === "object") {
+          var theme = palette.color.scheme === "slate" ? "dark" : "light"
+
+          /* Instruct Giscus to change theme */
+          var frame = document.querySelector(".giscus-frame")
+          frame.contentWindow.postMessage(
+            { giscus: { setConfig: { theme } } },
+            "https://giscus.app"
+          )
+        }
       })
     })
   </script>