2.x: document connection-idle-timeout (#9283)

* Add docs for connection-idle-timeout

docs/se/webserver/02_configuration.adoc

@@ -1,6 +1,6 @@
 ///////////////////////////////////////////////////////////////////////////////
 
-    Copyright (c) 2018, 2023 Oracle and/or its affiliates.
+    Copyright (c) 2018, 2024 Oracle and/or its affiliates.
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -85,6 +85,7 @@ Available socket configuration options:
 |`enabled` |`true` |boolean |A socket can be disabled through configuration, in which case it is never opened
 |`max-chunk-size` | `8192` |int |Maximal size of a chunk to read from incoming requests
 |`max-payload-size` | `-1` |long |Maximal size of a request payload in bytes. If exceeded a 413 error is returned. Negative value means no limit.
+|`connection-idle-timeout` | `0` |int |Timeout seconds after which any idle connection will be automatically closed. 0 means no timeout.
 |`backpressure-buffer-size` |long |`5242880` |Set a maximum length of the unflushed response data sending buffer can keep without applying backpressure.
 Depends on `backpressure-policy` what happens if max buffer size is reached.
 
@@ -108,4 +109,4 @@ Default is `LINEAR`
 |`requested-uri-discovery.trusted-proxies` |link:{common-http-javadoc-base-url}/AllowList.html[`AllowList`] |{nbsp} |Assigns the settings governing the acceptance and rejection of forwarded headers from incoming requests to this socket.
 This setting automatically enables discovery for the socket.
 |`requested-uri-discovery.types` |`(FORWARDED, X_FORWARDED, HOST)` (See link:{javadoc-base-url-api}/SocketConfiguration.RequestedUriDiscoveryType.html[`RequestedUriDiscoveryType`]) |`FORWARDED if discovery is enabled; none otherwise` |Assigns the front-end URI discovery type(s) this socket should use. This setting automatically enables discovery for the socket.
-|===
+|===