minor #3720 [#3539] A backport of a sentence - the parts that apply to 2.3 (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
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[#3539] A backport of a sentence - the parts that apply to 2.3

Hi guys!

| Q | A |
|----------------|------|
| Doc fix | no |
| New docs | no |
| Applies to | 2.3 |
| Fixed tickets | #3539 |

This backports the 2.3 parts of a paragraph that was added to 2.5 (master). I like to keep the branches different in *only* different features, so it's easy going into the future to merge things.

Thanks!

Commits
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3006120 [#3539] A backport of a sentence - the parts that apply to 2.3

Author: weaverryan

components/stopwatch.rst

@@ -35,6 +35,11 @@ microtime by yourself. Instead, use the simple
     // ... some code goes here
     $event = $stopwatch->stop('eventName');
 
+The :class:`Symfony\\Component\\Stopwatch\StopwatchEvent` object can be retrieved
+from the  :method:`Symfony\\Component\\Stopwatch\\Stopwatch::start`, 
+:method:`Symfony\\Component\\Stopwatch\\Stopwatch::stop` and
+:method:`Symfony\\Component\\Stopwatch\\Stopwatch::lap` methods.
+
 You can also provide a category name to an event::
 
     $stopwatch->start('eventName', 'categoryName');