fix: cookies doc

[vinckr]

Related Issue or Design Document

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
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• I have added tests that prove my fix is effective or that my feature works.
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Further comments

[Copilot]

Pull request overview

Updates the Ory Hydra “Configuring cookies” guide to better explain cookie-related configuration options (especially SameSite) and common browser/runtime constraints.

Changes:

• Expands SameSite documentation, including modern browser third-party cookie restrictions and legacy compatibility behavior.
• Adds sections describing cookie domain, path, names (including defaults), and development-mode Secure behavior.
• Updates configuration examples to reflect the recommended settings described in the guide.

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