docs: maintainer-pgp-guide.rst: add a reference for kernel.org sign

The media profile documentation will point to kernel.org sign.
Add a link to it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab 2025-09-02 12:02:18 +02:00
commit 54857c5245