Update Example 6.1

The type sonata_type_model_list replaces the fourth parameter in $formMapper->add()
Update outdated docs

Fixes https://github.com/sonata-project/SonataDoctrineORMAdminBundle/issues/5
Update outdated docs
Change required to false in sonata_type_model_list to avoid error "An invalid form control with name='' is not focusable"
Merge pull request #390 from pulzarraider/stml_fix

Change required option to false in sonata_type_model_list to avoid error "An invalid form control with name='' is not focusable"
Merge pull request #385 from webdevilopers/patch-2

Update outdated docs for doctrine_orm_callback
Merge pull request #383 from julialasarte/patch-1

Update doc Example 6.1
Fix incorrect route and ACL check for delete button
Merge pull request #238 from pulzarraider/delete_check_fix

Fix incorrect route and security check for delete button in oneToOne and manyToOne templates
Merge remote-tracking branch 'sonata-project/master'