docs: another auth method for ElasticsearchStore (#16831)

Users can also use their own Elasticsearch client object to configure
the connection.

docs/docs/integrations/vectorstores/elasticsearch.ipynb

@@ -92,6 +92,28 @@
     "        )\n",
     "```\n",
     "\n",
+    "You can also use an `Elasticsearch` client object that gives you more flexibility, for example to configure the maximum number of retries.\n",
+    "\n",
+    "Example:\n",
+    "```python\n",
+    "        import elasticsearch\n",
+    "        from langchain_community.vectorstores import ElasticsearchStore\n",
+    "\n",
+    "        es_client= elasticsearch.Elasticsearch(\n",
+    "            hosts=[\"http://localhost:9200\"],\n",
+    "            es_user=\"elastic\",\n",
+    "            es_password=\"changeme\"\n",
+    "            max_retries=10,\n",
+    "        )\n",
+    "\n",
+    "        embedding = OpenAIEmbeddings()\n",
+    "        elastic_vector_search = ElasticsearchStore(\n",
+    "            index_name=\"test_index\",\n",
+    "            es_connection=es_client,\n",
+    "            embedding=embedding,\n",
+    "        )\n",
+    "```\n",
+    "\n",
     "#### How to obtain a password for the default \"elastic\" user?\n",
     "\n",
     "To obtain your Elastic Cloud password for the default \"elastic\" user:\n",
@@ -134,7 +156,7 @@
    "id": "ea167a29",
    "metadata": {},
    "source": [
-    "We want to use `OpenAIEmbeddings` so we have to get the OpenAI API Key."
+    "To use the `OpenAIEmbeddings` we have to configure the OpenAI API Key in the environment."
    ]
   },
   {