[Developer/Testing] (#6334)

* Improve Testing

* Update index.md

* More tweaks

* Update index.md

* Fix formatting and improve clarity in testing guide

---------

Co-authored-by: Jim Walker <[email protected]>

Author: niels9001

.openpublishing.redirection.json

@@ -1,5 +1,15 @@
 {
   "redirections": [
+    {
+      "source_path": "hub/apps/winui/winui3/testing/index.md",
+      "redirect_url": "/windows/apps/develop/testing/",
+      "redirect_document_id": false
+    },
+    {
+      "source_path": "hub/apps/winui/winui3/testing/create-winui-unit-test-project.md",
+      "redirect_url": "/windows/apps/develop/testing/",
+      "redirect_document_id": false
+    },
     {
       "source_path": "hub/apps/performance/introduction.md",
       "redirect_url": "/windows/apps/performance/",