[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
[WCM] Skip console commands from event listeners

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#9235)
| Applies to    | master
| Fixed tickets | none
[Translation] added method to expose collected message
[OptionsResolver] Adjusted the OptionsResolver documentation to describe the 2.6 API
Added missing mailer class and use statements
Added a note about the total deprecation of YUI
Fixed the official name of Node.js
Reverted removal, removed API links instead
Removed duplicate use statements
tweaks to the contribution chapter
add note about parameters in imports
intro the var-dumper component
Added note about ProgressBar changes
add description for the `validation_groups` option
Added feature freeze dates for Symfony versions