[Daiyuanranfeng]

Fixes #155

Summary

• Point both context cipher-list setters to BoringSSL’s cipher-list syntax.
• Explain how the permissive and strict setters handle unrecognized entries, and clarify that neither setter changes TLS 1.3 cipher suites.

Validation

• Checked the behavior against the BoringSSL header pinned by this repository and verified the linked documentation anchor.
• cargo fmt --all -- --check and git diff --check passed. No runtime code changed.

[clanky-the-clanker]

This pull request was not reviewed automatically because its author does not have write access to this repository. A maintainer with write access can start a review by commenting clanky review (or clanker review or @clanky-the-clanker review), optionally followed by instructions (e.g. clanky review focus on the retry logic).