Turn off session resumption on wolfSSL servers verifying clients

wolfSSL shares its session cache between contexts, so a session resumed
on a server that checks client certificates could carry a certificate
checked against another server's CA, or against a client CA replaced
since. Such a server no longer resumes sessions.

README.md

@@ -72,6 +72,8 @@ cpp-httplib supports multiple TLS backends through an abstraction layer:
 
 > [!NOTE]
 > **wolfSSL limitation:** `get_ca_certs()` and `get_ca_names()` only reflect CA certificates loaded via `load_ca_cert_store()`. Certificates loaded through `set_ca_cert_path()` or system certificates (`load_system_certs`) are not enumerable.
+>
+> A wolfSSL server that verifies client certificates does not resume TLS sessions: wolfSSL shares its session cache between contexts, so a resumed session could carry a certificate checked against another server's client CA.
 
 > [!NOTE]
 > **BoringSSL (best-effort):** BoringSSL builds under `CPPHTTPLIB_OPENSSL_SUPPORT` and is exercised by CI against current upstream. Because BoringSSL does not guarantee API stability, support is best-effort — breakage may occasionally land. Two known behavioral differences vs OpenSSL: (1) BoringSSL's public headers require C++14 or later, so consumers must compile accordingly; (2) hostname verification is SAN-only per RFC 6125 §6.4.4 (no CN fallback).