Fixed description for session storage
feature #4076 Fixed description of session storage of the ApiKeyAuthenticator (peterrehm)

This PR was submitted for the master branch but it was merged into the 2.4 branch instead (closes #4076).

Discussion
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Fixed description of session storage of the ApiKeyAuthenticator

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.4
| Fixed tickets | #4060

I assume the authentication is needed for each request (even if token is stored in the session)
since you can add custom logic in the authenticator.

Commits
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f3c02dd Fixed description for session storage