Update README.md

Separate copy and paste commands, sort of like a GUI file browser.

OPTIONS:
  copy -c           Copies a list of files/folders, making them available for pasting later on.
  cut -cu           Does the same as copy, but deletes the original files/folders in the progress.
  paste -p          Pastes the marked files/folders from earlier to your current folder.
  help -h           Displays this information.

EXAMPLES:
  Mark a list of files/folders for copying:
  $PROGNAME copy file1 file2 file3 folder

  Cut a list of files/folders:
  $PROGNAME cut file1 file2 file3 folder

  Paste the marked files/folders to your current folder:
  $PROGNAME paste