doc: add version metadata to timers/promises

Refs: #33950

PR-URL: #36378
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Beth Griggs <[email protected]>
Reviewed-By: Richard Lau <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Daijiro Wachi <[email protected]>

Author: cjihrig

doc/api/timers.md

@@ -321,6 +321,9 @@ added: v0.0.1
 Cancels a `Timeout` object created by [`setTimeout()`][].
 
 ## Timers Promises API
+<!-- YAML
+added: v15.0.0
+-->
 
 > Stability: 1 - Experimental
 
@@ -333,6 +336,9 @@ const timersPromises = require('timers/promises');
 ```
 
 ### `timersPromises.setTimeout([delay[, value[, options]]])`
+<!-- YAML
+added: v15.0.0
+-->
 
 * `delay` {number} The number of milliseconds to wait before resolving the
   `Promise`. **Default**: `1`.
@@ -345,6 +351,9 @@ const timersPromises = require('timers/promises');
     cancel the scheduled `Timeout`.
 
 ### `timersPromises.setImmediate([value[, options]])`
+<!-- YAML
+added: v15.0.0
+-->
 
 * `value` {any} A value with which the `Promise` is resolved.
 * `options` {Object}