Security

@todo - write docs: general usage of expression language inside of "security" annotation
@todo - write docs: general usage of expression language inside of "security_post_denormalize" annotation
@todo - write docs: example usage of frontend user
@todo - write docs: example usage of frontend user group
@todo - write docs: example usage of backend user
@todo - write docs: example usage of backend user group
@todo - write docs: example usage of object in items operations (+ information that object doesn't exist in collection operation)
@todo - write docs: information that most of the conditions from typoscript can be used (https://docs.typo3 .org/m/typo3/reference-typoscript/master/en-us/Conditions/Index.html#description; tree is an example object which can not be used)