Document the new SHA256 and SHA512 password generation options

Reviewed-by: Rich Salz <rsalz@openssl.org>

CHANGES

@@ -6,6 +6,11 @@
 
   *)
 
+  *) 'openssl passwd' can now produce SHA256 and SHA512 based output,
+     using the algorithm defined in
+     https://www.akkadia.org/drepper/SHA-crypt.txt
+     [Richard Levitte]
+
  Changes between 1.0.2h and 1.1.0  [25 Aug 2016]
 
   *) Windows command-line tool supports UTF-8 opt-in option for arguments

doc/apps/passwd.pod

@@ -11,6 +11,8 @@ B<openssl passwd>
 [B<-crypt>]
 [B<-1>]
 [B<-apr1>]
+[B<-5>]
+[B<-6>]
 [B<-salt> I<string>]
 [B<-in> I<file>]
 [B<-stdin>]
@@ -48,6 +50,13 @@ Use the MD5 based BSD password algorithm B<1>.
 
 Use the B<apr1> algorithm (Apache variant of the BSD algorithm).
 
+=item B<-5>
+
+=item B<-6>
+
+Use the B<SHA256> / B<SHA512> based algorithms defined by Ulrich Drepper.
+See L<https://www.akkadia.org/drepper/SHA-crypt.txt>.
+
 =item B<-salt> I<string>
 
 Use the specified salt.