We changed the suffix of tarballs for Cargo-fetched packages, which affects out-of-tree packages, so it makes sense to document that in the migration guide. Reported-by: Julien Olivain <ju.o@free.fr> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>