Update http://docs.oracle.com/javase/8/docs/technotes/tools/windows/kinit.html to reflect enhancements made in the parent task.

- Updates the synopsis and commands part to be consistent with the new kinit -help output.
 
- Add a new section on "Time duration" formats, which is defined in http://web.mit.edu/kerberos/krb5-devel/doc/basic/date_format.html#duration.
 
- Add new examples:
 
  kinit user
     Request a TGT for user
 
  kinit -l 1h user
     Request a TGT for user that will expire in 1 hour
 
  kinit -l 1h -r 10h user
     Request a TGT for user that will expire in 1 hour but is renewable
     up to 10 hours. User must renew a ticket before it's expired.
     The renewed ticket can be renewed again and again within 10 hours
     from its initial request.
 
  kinit -R user
     Renew an existing renewable TGT for user