'^O' command documentation and '^' command help

'^O' command documentation and '^' command help

While looking for things in core which might conceivably trigger the
Windows ctype assertion failure (haven't found any yet), I noticed
that help_dir() was still treating ^O as a wizard mode-only command.
Also, documentation about that command was never brought up to date.

I wish this change to ^O hadn't been done.  #overview already has
a meta/alt M-O shortcut and overloading wizard mode commands makes
documentation more complicated since wizard mode stuff traditionally
has been left unmentioned.