Issues in the Setup article

[javiereguiluz]

Just reported on Symfony Slack:

Hi everyone.  I'm new here and I'm glad that there is a symfony community.

I noticed that on the main symfony.com/doc/current/setup.html page,
the instructions state to run symfony server:start before mentioning
that you need to run composer install before hand.

Also, although the documentation says that the xml extension is installed
by default, I had to explicitly install the xml extension on a clean
install in a ubuntu 20 virtual machine.

[wouterj]

I don't see the page mentioning that XML extensoin is installed by default. It only says: "which are installed and enabled by default in most PHP 7 installations"