bug#3527: 23.0.94; Setting the default font using `menu-set-font'

The `menu-set-font' doc string should explicitly say that this sets
the default font for _all frames_. It should also say that this
command _saves_ the new default for future Emacs sessions. It should
also mention that you can customize face `default' to do the same
thing.
 
This is a new feature. It is called out in NEWS (see entry `Menu Bar
changes'), but there is nothing in the doc string that indicates that
this is different from, say, `set-default-font'.
 
This also needs to be documented clearly in the Emacs manual - there
is nothing in the manual about this, AFAICT.  help-gnu-emacs queries
make it clear that it is unclear to users how to set the default font
- what are the various ways etc. The manual should be clear about
this, with cross refs among the various sections that describe
different ways to set the default font.

In GNU Emacs 23.0.94.1 (i386-mingw-nt5.1.2600)
 of 2009-05-24 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'