Add a migration subsection on the need to add MLPREFIX to conditional
package dependencies in gatesgarth.
(From yocto-docs rev: e202beabfc1282d6999fde0ced89e41c993da27f)
Signed-off-by: Paul Eggleton <paul.eggleton@microsoft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>