docs: document Crawlee storage clients and rename storages page

Author: vdusek

docs/01_introduction/quick-start.mdx

@@ -85,7 +85,7 @@ To learn more about the features of the Apify SDK and how to use them, check out
 
 - [Actor lifecycle](../concepts/actor-lifecycle)
 - [Actor input](../concepts/actor-input)
-- [Working with storages](../concepts/storages)
+- [Storages](../concepts/storages)
 - [Storage clients](../concepts/storage-clients)
 - [Actor events & state persistence](../concepts/actor-events)
 - [Proxy management](../concepts/proxy-management)

docs/02_concepts/03_storages.mdx

@@ -1,6 +1,6 @@
 ---
 id: storages
-title: Working with storages
+title: Storages
 description: Use datasets, key-value stores, and request queues to persist Actor data.
 ---
 

docs/02_concepts/12_storage_clients.mdx

@@ -30,6 +30,10 @@ The `apify.storage_clients` module provides the following clients:
 - <ApiLink to="class/FileSystemStorageClient">`FileSystemStorageClient`</ApiLink> — persists data to the local filesystem. Used as the default local client.
 - <ApiLink to="class/MemoryStorageClient">`MemoryStorageClient`</ApiLink> — keeps everything in memory only; nothing is persisted. Useful for tests and short-lived runs.
 
+All of these implement Crawlee's <ApiLink to="class/StorageClient">`StorageClient`</ApiLink> interface, so any of them can be used as a sub-client of `SmartApifyStorageClient` — see [customizing the storage client](#customizing-the-storage-client) below.
+
+Crawlee additionally ships storage clients backed by a self-hosted database — a [`RedisStorageClient`](https://crawlee.dev/python/api/class/RedisStorageClient) and a [`SqlStorageClient`](https://crawlee.dev/python/api/class/SqlStorageClient). The Apify SDK does not re-export these, because they each require an extra dependency that the SDK does not install. To use one, install the matching Crawlee extra (for example `pip install 'crawlee[redis]'` or `crawlee[sql-postgres]` / `crawlee[sql-sqlite]`), import the client from `crawlee.storage_clients`, and pass it as a sub-client of `SmartApifyStorageClient`. See the [Crawlee storage clients guide](https://crawlee.dev/python/docs/guides/storage-clients) for details.
+
 ## Single vs. shared request queue
 
 `ApifyStorageClient` supports two ways of accessing the Apify request queue, selected via its `request_queue_access` argument:

website/docusaurus.config.js

@@ -259,10 +259,6 @@ module.exports = {
                         url: 'https://crawlee.dev/python/api/class/FileSystemStorageClient',
                         group: 'Storage clients',
                     },
-                    {
-                        url: 'https://crawlee.dev/python/api/class/SqlStorageClient',
-                        group: 'Storage clients',
-                    },
                     // Request loaders
                     {
                         url: 'https://crawlee.dev/python/api/class/RequestLoader',