Add placeholder files to be populated for the next 5.3 release.
Relevant section names from the previous 5.2 release migration
guide/release note have been left with their content empty.
(From yocto-docs rev: 2822bf71ee7cd2fa48f2f802eaab236538112d85)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
