Remove discovery module from docs (#28450)

source/_integrations/discovery.markdown

@@ -1,78 +0,0 @@
----
-title: Discovery
-description: Instructions on how to setup Home Assistant to discover new devices with the Discovery integration.
-ha_category:
-  - Other
-ha_release: 0.7
-ha_quality_scale: internal
-ha_domain: discovery
-ha_codeowners:
-  - '@home-assistant/core'
-ha_integration_type: system
----
-
-This is the legacy discovery integration for Home Assistant. It's use is no longer recommended. Use the [SSDP](/integrations/ssdp/), [Zeroconf](/integrations/zeroconf/) and [USB](/integrations/usb/) integrations instead.
-
-This integration is limited to detect:
-
-- [Bluesound speakers](/integrations/bluesound)
-- [Bose Soundtouch speakers](/integrations/soundtouch)
-- [Enigma2 media player](/integrations/enigma2)
-- [SABnzbd downloader](/integrations/sabnzbd)
-- [Yamaha media player](/integrations/yamaha)
-
-To load this integration, add the following lines to your `configuration.yaml` file:
-
-```yaml
-# Example configuration.yaml entry
-discovery:
-  ignore:
-    - yamaha
-    - logitech_mediaserver
-```
-
-{% configuration discovery %}
-ignore:
-  description: A list of platforms that never will be automatically configured by `discovery`.
-  required: false
-  type: list
-enable:
-  description: A list of platforms not enabled by default that `discovery` should discover.
-  required: false
-  type: list
-{% endconfiguration %}
-
-Valid values for ignore are:
-
-- `bluesound`: Bluesound speakers
-- `bose_soundtouch`: Bose Soundtouch speakers
-- `enigma2`: Enigma2 media players
-- `lg_smart_device`: LG Soundbars
-- `sabnzbd`: SABnzbd downloader
-- `yamaha`: Yamaha media player
-
-## Troubleshooting
-
-### mDNS and UPnP
-
-Home Assistant should be on the same network as the devices for mDNS and UPnP discovery to work.
-
-When running Home Assistant Core in a [Docker container](/docs/installation/docker/) command line option `--net=host` or the compose file equivalent `network_mode: host` must be used to put it on the host's network, otherwise mDNS and UPnP will not work.
-
-If mDNS is still not working:
-- Make sure there are no firewall rules blocking mDNS traffic. mDNS relies on sending and receiving UDP multicast packets on port 5353.
-- mDNS traffic may not be forwarded correctly between the wired and wireless interfaces of a Wi-Fi AP or router.
-
-#### mDNS forwarding
-If it's not possible to have Home Assistant and the devices on the same network, mDNS forwarding may allow mDNS discovery between networks.
-
-mDNS forwarding is a configurable option in some routers. It can also be called mDNS reflector or mDNS repeater, depending on the manufacturer.
-
-### Windows
-
-#### 64-bit Python
-There is currently a <a href='https://web.archive.org/web/20200623234241/https://bitbucket.org/al45tair/netifaces/issues/17/dll-fails-to-load-windows-81-64bit'>known issue</a> with running this integration on a 64-bit version of Python and Windows.
-
-### Could not install dependency netdisco
-
-If you see `Not initializing discovery because could not install dependency netdisco==0.6.1` in the logs, you will need to install the `python3-dev` or `python3-devel` package on your system manually (eg. `sudo apt-get install python3-dev` or `sudo dnf -y install python3-devel`). On the next restart of Home Assistant, the discovery should work. If you still get an error, check if you have a compiler (`gcc`) available on your system.

source/_integrations/enigma2.markdown

@@ -17,7 +17,7 @@ The `enigma2` platform allows you to control a Linux based set-top box which is
 
 [OpenWebif](https://github.com/E2OpenPlugins/e2openplugin-OpenWebif) is an open source web interface for Enigma2 based set-top boxes.
 
-To manually add a set-top box to your installation, add the following to your `configuration.yaml` file:
+To add a set-top box to your installation, add the following to your `configuration.yaml` file:
 
 ```yaml
 # Example configuration.yaml entry

source/_integrations/yamaha.markdown

@@ -32,7 +32,8 @@ To add a Yamaha Network Receiver to your installation, add the following to your
 media_player:
   - platform: yamaha
 ```
-
+You **must** enable network standby on your receiver, or else startup of Home Assistant will hang if you
+have your receiver switched off.
 {% configuration %}
 name:
   description: Name of the device. This overrides the default name (often model number) that is returned by the device.
@@ -60,21 +61,6 @@ zone_names:
   type: list
 {% endconfiguration %}
 
-### Discovery notes
-
-- If the `discovery` integration is enabled, all units on the network
-  will be discovered using UPnP.
-- For receivers that support more than one zone, Home Assistant will
-  add one media player per zone supported by the player, named "$name
-  Zone 2" and "$name Zone 3".
-- If you specify `host` manually, you **must** enable network standby
-  on your receiver, or else startup of Home Assistant will hang if you
-  have your receiver switched off.
-- In some cases, auto-discovery fails due to a known bug in the
-  receiver's firmware. It is possible to manually specify the
-  receiver's IP address or via its hostname (if it is discoverable by
-  your DNS) then.
-
 ### Supported operations
 
 - Media players created by Yamaha support powering on/off, mute,