Remove unnecessary argument (#333)

Author: elastic-thanos

supporting-blog-content/evaluating-search-relevance-part-1/retrieve-and-rerank.ipynb

@@ -262,7 +262,6 @@
     "            yield {\n",
     "                \"_id\": docid,\n",
     "                \"_op_type\": \"index\",\n",
-    "                \"refresh\": \"wait_for\",\n",
     "                \"title\": doc_title,\n",
     "                \"txt\": doc_txt,\n",
     "            }\n",