bug#34504: 'pp' causally mentioned

[積丹尼 Dan Jacobson]

In (info "(emacs) Program Indent") it says:
   Emacs also provides a Lisp pretty-printer in the ‘pp’ package, which
reformats Lisp objects with nice-looking indentation."

OK, as there is no hyperlink to click on, say the user eventually finds
that indeed there is
$ dlocate /pp\\.
emacs-el: /usr/share/emacs/26.1/lisp/emacs-lisp/pp.el.gz
and loads it, but he still cannot use it because there is no further
example of how, provided, even within that file. E.g., you could mention
how to pretty print one's .emacs with it.