doc: fix https.timeout docs

`server.timeout` is a property, not a method

PR-URL: https://github.com/nodejs/node/pull/12039
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/https.md

@@ -30,11 +30,11 @@ added: v0.11.2
 
 See [`http.Server#setTimeout()`][].
 
-### server.timeout([msecs])
+### server.timeout
 <!-- YAML
 added: v0.11.2
 -->
-- `msecs` {number} Defaults to 120000 (2 minutes).
+- {number} Defaults to 120000 (2 minutes).
 
 See [`http.Server#timeout`][].