RELEASES: finalise policy

[cyphar]

We have used this release policy for a year and it seems to work well for everyone and we haven't received much feedback, so it seems reasonable to say that we are committed to this policy now.

Also, now that runc 1.4.0 has been released, there is no need to single out 1.1.x and earlier as no longer being supported, as latest-2 is now 1.2.x and thus 1.1.x would no longer be supported even with the new support model.

Signed-off-by: Aleksa Sarai [email protected]