Update releases doc with updated support timeline
Update releases doc with updated support timeline

Updates for 1.5 release and adds 1.6

Signed-off-by: Derek McGowan <e1c79a582b6629e6b39e9679f4bb964d25db4aa8@mcg.dev>

mikebrow/containerd,estesp/containerd,estesp/containerd,thaJeztah/containerd,dmcgowan/containerd,vdemeester/containerd,containerd/containerd,dmcgowan/containerd,thaJeztah/containerd,containerd/containerd,vdemeester/containerd,mikebrow/containerd