[v9.4.x] Docs: fix broken migration-guide (#69896)

docs: fix broken migration-guide

docs/sources/developers/plugins/migration-guide/_index.md

@@ -1,41 +0,0 @@
----
-aliases:
-  - ../../plugins/developing/migration-guide
-keywords:
-  - grafana
-  - plugins
-  - migration
-  - plugin
-  - documentation
-title: Migration guides
----
-
-<script>
-(function () {
-  // Previously all the migration docs were on a single page, and the different sections could be linked using URL hashes.
-  var anchorRedirects = {
-    "migrate-a-plugin-from-angular-to-react": "./angular-react/",
-    "from-version-62x-to-740": "./v6.x-v7.x#from-version-62x-to-740",
-    "from-version-65x-to-730": "./v6.x-v7.x#from-version-65x-to-730",
-    "from-version-6xx-to-700": "./v6.x-v7.x/",
-    "migrate-to-data-frames": "./v6.x-v7.x/",
-    "troubleshoot-plugin-migration": "./v6.x-v7.x/",
-    "from-version-7xx-to-8xx": "./v7.x-v8.x/",
-    "from-version-83x-to-84x": "./v8.3.x-8.4.x/",
-    "from-version-8x-to-9x": "./v8.x-v9.x/",
-    "from-version-91x-to-92x": "./v9.1.x-v9.2.x/",
-    "from-version-93x-to-94x": "./v9.3.x-9.4.x/",
-  };
-  var hash = window.location.hash.substring(1);
-  var redirectTo = anchorRedirects[hash];
-  if (redirectTo) {
-    window.location.replace(redirectTo);
-  }
-})();
-</script>
-
-# Plugin migration guide
-
-The following guides help you identify the steps required to update a plugin following changes between versions of Grafana.
-
-{{< section menuTitle="true">}}