Added/updated snippets for docs (#2318)

docs/doc_examples/8634c9993485d622fb12d24f4f242264.asciidoc

@@ -0,0 +1,23 @@
+// This file is autogenerated, DO NOT EDIT
+// Use `node scripts/generate-docs-examples.js` to generate the docs examples
+
+[source, js]
+----
+const response = await client.indices.modifyDataStream({
+  actions: [
+    {
+      remove_backing_index: {
+        data_stream: "my-data-stream",
+        index: ".ds-my-data-stream-2023.07.26-000001",
+      },
+    },
+    {
+      add_backing_index: {
+        data_stream: "my-data-stream",
+        index: ".ds-my-data-stream-2023.07.26-000001-downsample",
+      },
+    },
+  ],
+});
+console.log(response);
+----