Merge branch 'master' of git.openssl.org:openssl

Stupid git tricks :(

Reviewed-by: rsalz

doc/ssl/SSL_CTX_set_tmp_dh_callback.pod

diff --git a/doc/ssl/SSL_CTX_set_tmp_dh_callback.pod b/doc/ssl/SSL_CTX_set_tmp_dh_callback.pod
index 7a27eef..a9995fc 100644
--- a/doc/ssl/SSL_CTX_set_tmp_dh_callback.pod
+++ b/doc/ssl/SSL_CTX_set_tmp_dh_callback.pod
@@ -67,6 +67,7 @@
 has an impact on the computer time needed during negotiation, but it is not
 very large, so application authors/users should consider to always enable
 this option.
+The option is required to implement perfect forward secrecy (PFS).
 
 As generating DH parameters is extremely time consuming, an application
 should not generate the parameters on the fly but supply the parameters.