Sample etc/kamailio.cfg: add tls_threads_mode to config

etc/kamailio.cfg

@@ -220,6 +220,13 @@ enable_tls=yes
 
 /* upper limit for TLS connections */
 tls_max_connections=2048
+
+/* For OpenSSL 3 integration
+ * functions calling libssl3 can be invoked in a transient thread
+ * 0: disable threaded calls
+ * 1: use threads for process#0 only
+ * 2: use threads for all processes */
+tls_threads_mode=1
 #!endif
 
 /* set it to yes to enable sctp and load sctp.so module */