Document the change in req.

 Changes between 0.9.5a and 0.9.6  [xx XXX 2000]

  *) Addition of the command line parameter '-rand file' to 'openssl req'.

     The given file takes precedence over the RANDFILE option in the

     configuration file.

     The given file adds to whatever has already been seeded into the

     random pool through the RANDFILE configuration file option or

     environment variable, or the default random state file.

     [Richard Levitte]

  *) mkstack.pl now sorts each macro group into lexical order.