Update some code

[Iam-WenYi]

No description provided.

[javiereguiluz]

@IamBeginnerC thanks for improving this!

Before merging, let me ask one of your maintainers (@wouterj) because I'm not sure about the exact branch in which to merge this and Wouter knows it well. Thanks!

[wouterj]

4.4 it is :)

For full reference:

Description	Version
Classes without parent	Parameter and return types in 4.4 (if supported in PHP 7.1+)
Classes extending/implementing Symfony classes/interfaces	Return types in 4.4 (if supported in PHP 7.1+); Parameter types in 5.4

[javiereguiluz]

Thanks Wouter! I'll take note about this for future contributions 🙏

@IamBeginnerC thanks and congrats on your first Symfony Docs contribution 🎉