bug#70140: Missing ./doc/guix-cookbook.pt_BR.texi

[Rostislav Svoboda]

Hello Florian,

> Would that be OK?

Yeah, that's it. Sure, it's not much but it is at least "something" we
can refer to and later improve upon.

Here is a different wording of your text (,aided by AI. Pick the one
of your liking and commit it please):

Should @command{make} fail with a new error message after updating, it
is recommended to revisit and repeat the steps outlined in this section,
commencing with @command{./bootstrap}.

Thanks & Cheers