Add PRNGD link.

doc/crypto/RAND_egd.pod

@@ -21,6 +21,10 @@ RAND_egd() is called with that path as an argument, it tries to read
 random bytes that EGD has collected. The read is performed in
 non-blocking mode.
 
+Alternatively, the EGD-compatible daemon PRNGD can be used. It is
+available from
+http://www.aet.tu-cottbus.de/personen/jaenicke/postfix_tls/prngd.html .
+
 =head1 RETURN VALUE
 
 RAND_egd() returns the number of bytes read from the daemon on