Improved the phpdoc for security token classes
minor #12310 Improved the phpdoc for security token classes (stof)

This PR was merged into the 2.3 branch.

Discussion
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Improved the phpdoc for security token classes

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

This will avoid to have Scrutinizer complaining that we pass an array of string rather than an array of RoleInterface for instance.

Commits
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7b6d115 Improved the phpdoc for security token classes