As suggested in bug#41198, here is a patch that adds
two new options (disabled by default):

- outline-minor-mode-font-lock that enables outline font-lock in
  outline-minor-mode

- outline-minor-mode-cycle that enables heading cycle in
  outline-minor-mode

And at the end of the patch are two examples that enable this feature
in the files etc/compilation.txt and etc/grep.txt.  So visiting these files
will highlight their outline headers, and will allow typing 'TAB' to cycle
between `hide all', `headings only' and `show all' when point is on the heading line.
Typing 'S-TAB' on the heading line cycles the whole buffer.  Typing these keys
anywhere outside heading lines uses their default bindings, so TAB will go
to the next link, and S-TAB will navigate back to the previous link.