Small changes on documentation

Hello and lots of thanks for this module

Problem/Motivation

I have updated fields to media and I had to apply the patch to run drush in Drupal 10.
https://www.drupal.org/project/migrate_file_to_media/issues/3399135#comm... 🐛 Drush Generator commands are not working in Drush 12.3.0.0 RTBC
Also, I think that in the README.md it would be good to advice about the difference of creating the module or using a pre-existing one.
I mean, put it when
"The generator will ask you several questions about the module, the source bundle and the target media entity.
It will generate several files based on your answers, that can be used to migrate the files to media entity."

Steps to reproduce

Run drush generate migrate_file_to_media:media_migration_generator:v2
produces the following result
Command "migrate_file_to_media.media_migration_generator.v2" is not defined.

Proposed resolution

When the patch is accepted, change the documentation.
I can make the patch.

Thanks again!!! Solved my day!