remove part about adding extension

[tuanalumi]

I do not really understand this paragraph and did not follow it, but the constraints option still works. So I believe it is something historical.

[wouterj]

This is done for automatically when you're using the Symfony framework and is only something you should care about if you're using the Form component in a standalone project.

But as this is the main guide everyone will read, I agree with removing it here, it'll only cause confusion.

So thanks for reporting & fixing confusing bits of the docs! 👍

status: reviewed

[xabbuh]

Thank you @tuanalumi.