Add QBittorrent's alternative speed switch doc (#30738)

* Add QBittorrent's alternative speed switch doc

* Fix typo

* Fix typo again

* Make coderabit happy

* Fix typo and change switch description

* Update source/_integrations/qbittorrent.markdown

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Fix bad merge

* Update qbittorrent.markdown

* Apply sentence-style capitalization

It matches the spelling used in the UI string

* tweak

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

source/_integrations/qbittorrent.markdown

@@ -12,10 +12,12 @@ ha_codeowners:
   - '@finder39'
 ha_platforms:
   - sensor
+  - switch
 ha_integration_type: service
 ---
 
 The `qbittorrent` platform allows you to monitor your downloads with [qBittorrent](https://www.qbittorrent.org/) from within Home Assistant and setup automations based on the information.
+You can control the alternative speed via the `Alternative speed` switch.
 
 ## Setup
 
@@ -35,6 +37,12 @@ The qBittorrent integration will add the following sensors:
 - `sensor.qbittorrent_inactive_torrents`: The current inactive torrents in qBittorrent.
 - `sensor.qbittorrent_paused_torrents`: The current paused torrents in qBittorrent.
 
+## Switch
+
+The qBittorrent integration adds the following switch:
+
+- `Alternative speed`: Allows you to enable or disable qBittorrent's alternative speed.
+
 ## Actions
 
 ### Action `qbittorrent.get_torrents`