bug#67449: Manual: add how to change default global font size in .emacs

[Dan Jacobson <jidanni@jidanni.org>]

In (info "(emacs) Fonts")

> File: emacs.info,  Node: Fonts,  Next: Speedbar,  Prev: Frame Commands,  Up: Frames
> 
> 22.8 Fonts
> ==========
> 
> By default, Emacs displays text on graphical displays using a 10-point

10 point. Let's say we want it to use 14 point default.

> monospace font,

We don't care about monospace or not. We just want to make 10 into 14.


> and the font size can be changed interactively (*note
> Text Scale::).

We don't want to change it interactively. We just want to put a line in
our .emacs file to change it.

>    There are several different ways to specify a different font:

We don't want to specify a different font. We don't care about the font.
We just want to make it use a different size as default.

>    • Click on ‘Set Default Font’ in the ‘Options’ menu.  This makes the
>      selected font the default on all existing graphical frames.  To
>      save this for future sessions, click on ‘Save Options’ in the
>      ‘Options’ menu.

We don't want to click on anything. Nor do we want to choose a font. We
just want to change the default size for emacs of fonts.

> 
>    • Add a line to your init file, modifying the variable
>      ‘default-frame-alist’ to specify the ‘font’ parameter (*note Frame
>      Parameters::), like this:
> 
>           (add-to-list 'default-frame-alist
>                        '(font . "DejaVu Sans Mono-10"))

Yes we want to add a line to our .emacs file. But we don't want to have
to say some font name. We just want to tell emacs to use "default size
14, not 10".


> 
>      This makes the font the default on all graphical frames created
>      after restarting Emacs with that init file.
> 
>    • Add an ‘emacs.font’ X resource setting to your X resource file,
>      like this:
> 
>           emacs.font: DejaVu Sans Mono-12

Again we are forced to name a font. We don't want to name a font. We
just want to tell emacs to do what it does, but at scale 14 not 10.

Anyway maybe there is a glimmer of hope with some line like
-*-*-*-14-*-*-*- or something, but it so frustrating. Whereas in other
apps one can just choose a default font size, in emacs ... well you have
to go down to the car dealership and learn about muffler types. You
can't just tell the rental agency to deliver an economy sized car.