doc: fix "timout" typo in timeout

Corrected to `timeout`

PR-URL: https://github.com/nodejs/node/pull/8231
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Yorkie Liu <yorkiefixer@gmail.com>
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/timers.md

@@ -50,9 +50,9 @@ added: v0.9.1
 When called, the active `Timeout` object will not require the Node.js event loop
 to remain active. If there is no other activity keeping the event loop running,
 the process may exit before the `Timeout` object's callback is invoked. Calling
-`timout.unref()` multiple times will have no effect.
+`timeout.unref()` multiple times will have no effect.
 
-*Note*: Calling `timout.unref()` creates an internal timer that will wake the
+*Note*: Calling `timeout.unref()` creates an internal timer that will wake the
 Node.js event loop. Creating too many of these can adversely impact performance
 of the Node.js application.