[bug#55321] Document building for foreign architectures

[Ludovic Courtès]

Hi!

I’m late to the party but I’d like to contribute this: 👍

Some nitpicking though:

> +Foreign architectures
> +* Using cross-compilation::  Build for foreign architecture using 
> cross-compilation.
> +* Using native building::    Build for foreign architectures natively.

Please use “title case” for node and section names, as in:

  Foreign Architectures

> +You might need to use GNU Guix to produce packages (@pxref{Invoking guix
> +package}), packs (@pxref{Invoking guix pack}) or even full systems
> +(@pxref{Invoking guix system}) targeting computers with different CPU
> +architectures than the one of your current CPU.
> +
> +GNU Guix supports two distinct mechanisms to target foreign

As a rule of thumb, I think it’s good to avoid repeating “GNU Guix”
because the reader most likely knows that it’s the manual they’re
reading :-) and because we can often be more precise or less verbose.
In this case, we could write:

  You can build packages, packs, or even full systems targeting
  computers with a different CPU architecture than the CPU you are
  using, or running a different operating system.

> +@item
> +The second one, called native building, consists in building using the
> +CPU instruction set of the foreign system you are targeting.  It often
> +requires emulation, using the QEMU program for instance.

> +The targets are specified as GNU triplets (@pxref{Specifying Target

s/The targets/Targets/  (or “Cross-compilation targets”?)

> +@node Using native building
> +@section Using native building

Or: “Native Builds”?  (“Using […] building” sounds weird to me.)

That’s all, thank you!  :-)

Ludo’.