Update A2 for clarity

[zanelow]

It was clear that API key should only be used for authorization and i felt that it should be indicated as such.

[ErezYalon]

Thanks for the contribution! Since this PR was opened, the repository restructured how content is organized: source files moved from 2019/en/src/<file>.md to editions/2019/en/<file>.md (no more src/ subfolder). Your change currently targets 2019/en/src/0xa2-broken-user-authentication.md, which no longer exists — that's why GitHub reports a merge conflict.

Could you rebase onto the latest develop and reapply your one-word fix to editions/2019/en/0xa2-broken-user-authentication.md? Happy to merge once it's aligned with the current layout.