[2.3] Examples that points to the DataCollectorListener should be removed.
[Security] Added remote_user firewall info and documentation for pre authenticated firewalls
[Reference][Configuration] Removed version added for remote_user
rebased using x509 pr, added remote_user pre authenticated part
fix missing backtick, rephrased bottom note
fixes missing backtick
Removed outdated translations from the official list
[OptionsResolver] Adjusted the OptionsResolver documentation to describe the 2.6 API
Added custom format page to translation component
Link from introduction section
Small fixes
Cleanups
Fixed version for composer install
Added missing mailer class and use statements
Improvements based on comments
Extra improvements based on comments
Fixed wrong indentation
Improved custom formats article based on comments
Added note about exporting SYMFONY_ENV
add link to form testing chapter in test section