bug#68505: [PATCH v2] Add more detailed instructions into the HACKING file.

[Ludovic Courtès]

Tomas Volf <~@wolfsden.cz> skribis:

> Until now, the ./meta/guile was not mentioned anywhere, and therefore it
> was not obvious how to run the locally compiled Guile without installing
> it.
>
> While modifying the file, I took the liberty to also mention a bit about
> compiling Guile using Guix.
>
> Finally, the header lines where cleaned up, ensuring all of them end at
> 70 and have a leading space.
>
> * HACKING (Hacking It Yourself): Add Guix instructions.  Add a note
> about meta/guile script.
> (Sample GDB Initialization File),
> (Naming conventions): Clean up the header line.

Applied, thanks!