doc: fix the timing of setImmediate's execution

About setImmediate, the execution timing is after timers currently.

PR-URL: nodejs#12034
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/timers.md

@@ -75,9 +75,7 @@ added: v0.9.1
 * `...args` {any} Optional arguments to pass when the `callback` is called.
 
 Schedules the "immediate" execution of the `callback` after I/O events'
-callbacks and before timers created using [`setTimeout()`][] and
-[`setInterval()`][] are triggered. Returns an `Immediate` for use with
-[`clearImmediate()`][].
+callbacks. Returns an `Immediate` for use with [`clearImmediate()`][].
 
 When multiple calls to `setImmediate()` are made, the `callback` functions are
 queued for execution in the order in which they are created. The entire callback