[Backport 8.15] Added/updated snippets for docs (#2319)

(cherry picked from commit f737290d10)

Co-authored-by: Josh Mock <joshua.mock@elastic.co>

docs/doc_examples/53aa8b21e2b1c4d48960343711296704.asciidoc

@@ -0,0 +1,15 @@
+// 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.search({
+  index: "my-index-000001",
+  query: {
+    regexp: {
+      "my_field.keyword": "a\\\\.*",
+    },
+  },
+});
+console.log(response);
+----