docs: clarify matching behavior for --peer-cert-allowed-cn and --cert-allowed-hostname flags

[AshrafAhmed9]

Closes #1062

Summary

Adds two clarifying sentences to the --peer-cert-allowed-cn section of the security documentation (v3.5, v3.6, v3.7) to explain the exact matching semantics:

• --peer-cert-allowed-cn performs an exact string comparison against the certificate's Common Name (CN) field — no wildcards or prefix matching is supported.
• • --peer-cert-allowed-hostname and --client-cert-allowed-hostname use Go's x509.Certificate.VerifyHostname(), which supports both exact hostnames and wildcard entries (e.g. *.example.com).
    This distinction was not previously documented and caused confusion for users who expected wildcard support in the CN flag.

Files Changed

• content/en/docs/v3.5/op-guide/security.md
• • content/en/docs/v3.6/op-guide/security.md
• • content/en/docs/v3.7/op-guide/security.md

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