Tried to clarify #3255
Rewording security sections to be even more clear that secure_channel and ip don't actually *restrict* access
Merge pull request #3256 from WouterJ/clarify_checking

[#3255] Tried to clarify how to check a box
fixes #3267

Make sure we use camelCase for action arguments
Merge pull request #3268 from greg0ire/argument_naming_consistency

fixes #3267
Merge pull request #3259 from symfony/security-access-control

Security access_control reword
Add gender-neutrality to documentation standards

Modeled after changes made to the Django project:
https://github.com/django/django/commit/c0a2daad78c66def2ce6592977b78dab6475dd53
typos and CS fixed