[Bug libstdc++/57226] The installation of pretty printers is not documented

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57226

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah, I haven't seen that warning.  If you'd mentioned that warning I would have
agreed it might be worth documenting, but as you only talked about how to
install them (which happens automatically) I didn't understand the issue.

I'll see what I can do to document it, maybe in the FAQ.