http: add server.keepAliveTimeoutBuffer option

PR-URL: https://github.com/nodejs/node/pull/59243
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Jason Zhang <xzha4350@gmail.com>

doc/api/http.md

@@ -1942,18 +1942,39 @@ added: v8.0.0
 
 The number of milliseconds of inactivity a server needs to wait for additional
 incoming data, after it has finished writing the last response, before a socket
-will be destroyed. If the server receives new data before the keep-alive
-timeout has fired, it will reset the regular inactivity timeout, i.e.,
-[`server.timeout`][].
+will be destroyed.
+
+This timeout value is combined with the
+\[`server.keepAliveTimeoutBuffer`]\[] option to determine the actual socket
+timeout, calculated as:
+socketTimeout = keepAliveTimeout + keepAliveTimeoutBuffer
+If the server receives new data before the keep-alive timeout has fired, it
+will reset the regular inactivity timeout, i.e., [`server.timeout`][].
 
 A value of `0` will disable the keep-alive timeout behavior on incoming
 connections.
-A value of `0` makes the http server behave similarly to Node.js versions prior
+A value of `0` makes the HTTP server behave similarly to Node.js versions prior
 to 8.0.0, which did not have a keep-alive timeout.
 
 The socket timeout logic is set up on connection, so changing this value only
 affects new connections to the server, not any existing connections.
 
+### `server.keepAliveTimeoutBuffer`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {number} Timeout in milliseconds. **Default:** `1000` (1 second).
+
+An additional buffer time added to the
+[`server.keepAliveTimeout`][] to extend the internal socket timeout.
+
+This buffer helps reduce connection reset (`ECONNRESET`) errors by increasing
+the socket timeout slightly beyond the advertised keep-alive timeout.
+
+This option applies only to new incoming connections.
+
 ### `server[Symbol.asyncDispose]()`
 
 <!-- YAML