[bug#71502] [PATCH][DOCUMENTATION] doc: Clarify when to use guix style when submitting patches.

[altadil]

Make more explicit the need to run guix style for new packages only,
not for updates.

* doc/contributing.texi (Submitting Patches): clarify the fourth item
of the checklist.

Change-Id: I69e1a6144b4da4814d2c8d9b44c7f77490183556
---
A newbie like me can easily miss the "new" here and mix guix style with
other changes. So let’s make it extra clear.
 doc/contributing.texi | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/doc/contributing.texi b/doc/contributing.texi
index b8adc169d8..33ef94bba3 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -1891,8 +1891,10 @@ name of the new or modified package, and fix any errors 
it reports
 (@pxref{Invoking guix lint}).
 
 @item
-Run @code{guix style @var{package}} to format the new package definition
-according to the project's conventions (@pxref{Invoking guix style}).
+For a new package, run @code{guix style @var{package}} to format the package
+definition according to the project's conventions (@pxref{Invoking guix 
style}).
+For an update to an existing package, it’s better to skip this step, as it
+would make reviewing the changes harder.
 
 @item
 Make sure the package builds on your platform, using @code{guix build
-- 
2.45.1