Update readme.md

[matudelatower]

• add support Symfony 5.

to change upload folder i.e. to packages/ckfinder.yaml:

ckfinder:
  connector:
    authenticationClass: App\CustomCKFinderAuth\CustomCKFinderAuth
    backends:
      default:
        name: default
        baseUrl: '%app.path.novedad_files%/'
        root: '%kernel.project_dir%/public%app.path.novedad_files%'