mention that EGD is used in non-blocking mode.

doc/crypto/RAND_egd.pod

@@ -18,7 +18,8 @@ EGD is available from http://www.lothar.com/tech/crypto/ (C<perl
 Makefile.PL; make; make install> to install). It is run as B<egd>
 I<path>, where I<path> is an absolute path designating a socket. When
 RAND_egd() is called with that path as an argument, it tries to read
-random bytes that EGD has collected.
+random bytes that EGD has collected. The read is performed in
+non-blocking mode.
 
 =head1 RETURN VALUE