Akeneo 3.2 to 4.0 documentation suggests rector version that doesn't work anymore

[lgoebkes]

In the documentation for migrating from 3.2 to 4.0 it is suggested to install rector with:
composer require --dev rector/rector

Currently it tries to install a version that clashes with other dependencies of symfony.
I changed it locally to rector/rector-prefixed which installs but has no scan-fatal-errors command and can not work with the supplied rector.yml configuration anymore.

Easy fix is to use:
composer require rector/rector-prefixed:^0.6.0

This version contains the mentioned command and allows the usage of the provided rector.yml.

I could open a PR for it if it helps.

Maybe you want to go another route:
Probably it would be better to update the configuration file to the new php version and use the new rector --dry-run instead of scan-fatal-errors command but this would be done in another repository, am I right?