doc: add history to http.request.setTimeout()

PR-URL: #25121 Refs: #8895 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: James M Snell <jasnell@gmail.com>

Author: jbunton-atlassian

doc/api/http.md

@@ -695,6 +695,10 @@ Once a socket is assigned to this request and is connected
 ### request.setTimeout(timeout[, callback])
 <!-- YAML
 added: v0.5.9
+changes:
+ - version: v9.0.0
+ pr-url: https://github.com/nodejs/node/pull/8895
+ description: Consistently set socket timeout only when the socket connects.
 -->
 
 * `timeout` {number} Milliseconds before a request times out.