…nt (simivar)

This PR was submitted for the 5.x branch but it was squashed and merged into the 5.2 branch instead.

Discussion
----------

[Stopwatch] Document new "name" property of StopwatchEvent

| Q             | A
| ------------- | ---
| Branch?       | 5.x <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | #37676 <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->
<!--
Replace this notice by a short README for your feature/bugfix. This will help people
understand your PR and can be used as a start for the documentation.

Additionally (see https://symfony.com/releases):
 - Always add tests and ensure they pass.
 - Never break backward compatibility (see https://symfony.com/bc).
 - Bug fixes must be submitted against the lowest maintained branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too.)
 - Features and deprecations must be submitted against branch 5.x.
 - Changelog entry should follow https://symfony.com/doc/current/contributing/code/conventions.html#writing-a-changelog-entry
-->

In Pull Request #37676 a new property was added to the `StopwatchEvent` which was not documented in `CHANGELOG.md` file

Commits
-------

de43e36 [Stopwatch] Document new "name" property of StopwatchEvent