docs: improved vectorstore notebooks (#3724)

- Added links to the vectorstore providers
- Added installation code (it is not clear that we have to go to the
`LangChan Ecosystem` page to get installation instructions.)

docs/modules/indexes/vectorstores/examples/elasticsearch.ipynb

@@ -7,14 +7,135 @@
    "source": [
     "# ElasticSearch\n",
     "\n",
-    "This notebook shows how to use functionality related to the ElasticSearch database."
+    "[Elasticsearch](https://www.elastic.co/elasticsearch/) is a distributed, RESTful search and analytics engine. It provides a distributed, multitenant-capable full-text search engine with an HTTP web interface and schema-free JSON documents.\n",
+    "\n",
+    "This notebook shows how to use functionality related to the `Elasticsearch` database."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "b66c12b2-2a07-4136-ac77-ce1c9fa7a409",
+   "metadata": {
+    "tags": []
+   },
+   "source": [
+    "## Installation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "81f43794-f002-477c-9b68-4975df30e718",
+   "metadata": {},
+   "source": [
+    "Check out [Elasticsearch installation instructions](https://www.elastic.co/guide/en/elasticsearch/reference/current/install-elasticsearch.html).\n",
+    "\n",
+    "To connect to an Elasticsearch instance that does not require\n",
+    "login credentials, pass the Elasticsearch URL and index name along with the\n",
+    "embedding object to the constructor.\n",
+    "\n",
+    "Example:\n",
+    "```python\n",
+    "        from langchain import ElasticVectorSearch\n",
+    "        from langchain.embeddings import OpenAIEmbeddings\n",
+    "\n",
+    "        embedding = OpenAIEmbeddings()\n",
+    "        elastic_vector_search = ElasticVectorSearch(\n",
+    "            elasticsearch_url=\"http://localhost:9200\",\n",
+    "            index_name=\"test_index\",\n",
+    "            embedding=embedding\n",
+    "        )\n",
+    "```\n",
+    "\n",
+    "To connect to an Elasticsearch instance that requires login credentials,\n",
+    "including Elastic Cloud, use the Elasticsearch URL format\n",
+    "https://username:password@es_host:9243. For example, to connect to Elastic\n",
+    "Cloud, create the Elasticsearch URL with the required authentication details and\n",
+    "pass it to the ElasticVectorSearch constructor as the named parameter\n",
+    "elasticsearch_url.\n",
+    "\n",
+    "You can obtain your Elastic Cloud URL and login credentials by logging in to the\n",
+    "Elastic Cloud console at https://cloud.elastic.co, selecting your deployment, and\n",
+    "navigating to the \"Deployments\" page.\n",
+    "\n",
+    "To obtain your Elastic Cloud password for the default \"elastic\" user:\n",
+    "1. Log in to the Elastic Cloud console at https://cloud.elastic.co\n",
+    "2. Go to \"Security\" > \"Users\"\n",
+    "3. Locate the \"elastic\" user and click \"Edit\"\n",
+    "4. Click \"Reset password\"\n",
+    "5. Follow the prompts to reset the password\n",
+    "\n",
+    "Format for Elastic Cloud URLs is\n",
+    "https://username:password@cluster_id.region_id.gcp.cloud.es.io:9243.\n",
+    "\n",
+    "Example:\n",
+    "```python\n",
+    "        from langchain import ElasticVectorSearch\n",
+    "        from langchain.embeddings import OpenAIEmbeddings\n",
+    "\n",
+    "        embedding = OpenAIEmbeddings()\n",
+    "\n",
+    "        elastic_host = \"cluster_id.region_id.gcp.cloud.es.io\"\n",
+    "        elasticsearch_url = f\"https://username:password@{elastic_host}:9243\"\n",
+    "        elastic_vector_search = ElasticVectorSearch(\n",
+    "            elasticsearch_url=elasticsearch_url,\n",
+    "            index_name=\"test_index\",\n",
+    "            embedding=embedding\n",
+    "        )\n",
+    "```"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": null,
+   "id": "d6197931-cbe5-460c-a5e6-b5eedb83887c",
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [],
+   "source": [
+    "!pip install elasticsearch"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "67ab8afa-f7c6-4fbf-b596-cb512da949da",
+   "metadata": {
+    "tags": []
+   },
+   "outputs": [
+    {
+     "name": "stdin",
+     "output_type": "stream",
+     "text": [
+      "OpenAI API Key: ········\n"
+     ]
+    }
+   ],
+   "source": [
+    "import os\n",
+    "import getpass\n",
+    "\n",
+    "os.environ['OPENAI_API_KEY'] = getpass.getpass('OpenAI API Key:')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "f6030187-0bd7-4798-8372-a265036af5e0",
+   "metadata": {
+    "tags": []
+   },
+   "source": [
+    "## Example"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
    "id": "aac9563e",
-   "metadata": {},
+   "metadata": {
+    "tags": []
+   },
    "outputs": [],
    "source": [
     "from langchain.embeddings.openai import OpenAIEmbeddings\n",
@@ -25,9 +146,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 5,
    "id": "a3c3999a",
-   "metadata": {},
+   "metadata": {
+    "tags": []
+   },
    "outputs": [],
    "source": [
     "from langchain.document_loaders import TextLoader\n",
@@ -43,7 +166,9 @@
    "cell_type": "code",
    "execution_count": null,
    "id": "12eb86d8",
-   "metadata": {},
+   "metadata": {
+    "tags": []
+   },
    "outputs": [],
    "source": [
     "db = ElasticVectorSearch.from_documents(docs, embeddings, elasticsearch_url=\"http://localhost:9200\")\n",
@@ -105,7 +230,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.1"
+   "version": "3.10.6"
   }
  },
  "nbformat": 4,