New manual page for a hardly known but important item :-)

doc/ssl/ssl.pod

diff --git a/doc/ssl/ssl.pod b/doc/ssl/ssl.pod
index c0eb400..00e27ea 100644
--- a/doc/ssl/ssl.pod
+++ b/doc/ssl/ssl.pod
@@ -657,6 +657,7 @@
 L<SSL_CTX_new(3)|SSL_CTX_new(3)>,
 L<SSL_CTX_set_client_CA_list(3)|SSL_CTX_set_client_CA_list(3)>,
 L<SSL_CTX_set_default_passwd_cb(3)|SSL_CTX_set_default_passwd_cb(3)>,
+L<SSL_CTX_set_session_id_context(3)|SSL_CTX_set_session_id_context(3)>,
 L<SSL_CTX_set_ssl_version(3)|SSL_CTX_set_ssl_version(3)>,
 L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>,
 L<SSL_CTX_use_certificate(3)|SSL_CTX_use_certificate(3)>,