Expand the overview section of the docs

Author: miguelgrinberg

docs/reference/index.md

@@ -11,6 +11,35 @@ This documentation covers the [official Python client for {{es}}](https://github
 
 API reference documentation is provided on [Read the Docs](https://elasticsearch-py.readthedocs.io).
 
+This client is composed of several modules:
+
+* The actual client, sometimes also called the "low-level" client
+
+   This module implements the client support for sending requests to {{es}} servers. The entire surface of the {{es}} API is available through this module.
+
+   * [Features](#_features)
+   * [Reference documentation](https://elasticsearch-py.readthedocs.io/en/stable/es_api.html)
+
+* Bulk helpers
+
+   The bulk helpers are a set of functions that use the low-level client's bulk ingest functions, but export a high-level interface based on Python iterables to simplify the ingest of large amounts of data.
+
+   * [User guide](https://www.elastic.co/docs/reference/elasticsearch/clients/python/client-helpers#bulk-helpers)
+   * [Reference documentation](https://elasticsearch-py.readthedocs.io/en/stable/api_helpers.html)
+
+* ES|QL query builder
+
+   This module offers an idiomatic interface to construct ES|QL queries based on Python expressions.
+
+   * [User guide](https://www.elastic.co/docs/reference/elasticsearch/clients/python/esql-query-builder)
+   * [Reference documentation](https://elasticsearch-py.readthedocs.io/en/stable/esql.html)
+
+* DSL module
+
+    The DSL module could be thought of as a high-level client for {{es}}. It allows applications to manipulate documents and queries using classes and objects instead of primitive types such as dictionaries and lists.
+
+    * [User guide](https://www.elastic.co/docs/reference/elasticsearch/clients/python/elasticsearch-dsl)
+    * [Reference documentation](https://elasticsearch-py.readthedocs.io/en/stable/dsl.html)
 
 The following example shows a simple Python client use case:
 
@@ -51,13 +80,7 @@ The client also provides a convenient set of [helpers](client-helpers.md) for ta
 To get started, try this walkthrough: [Ingest data with Python](docs-content://manage-data/ingest/ingesting-data-from-applications/ingest-data-with-python-on-elasticsearch-service.md)
 ::::
 
-### Elasticsearch Python DSL [_elasticsearch_python_dsl]
-
-The [Python DSL module](../reference/elasticsearch-dsl.md) offers a convenient and idiomatic way to write and manipulate queries. 
-
-## {{es}} version compatibility [_compatibility]
-
-Language clients are **forward compatible**: each client version works with equivalent and later minor versions of the **same or next major** version of {{es}}. For full compatibility, the client and {{es}} minor versions should match.
+## Compatibility [_compatibility]
 
 | Client version | {{es}} `8.x` | {{es}} `9.x` | {{es}} `10.x` |
 |----------------|---------------------------------|---------------------------------|----------------------------------|
@@ -82,4 +105,4 @@ In the Python client, compatibility mode is always enabled.
 
 :::{tip}
 To support working with multiple client versions, the Python client is also released under the package names `elasticsearch8` and `elasticsearch9` (to prevent name collisions).
-:::
+:::