internal: FIXME notes for container package set

Tracing the package set and repository journey, I found that the
container package defined on the image type is never really used.

Added notes to fix later.

internal/distro/rhel9/edge.go

@@ -38,7 +38,7 @@ var (
 			osPkgsKey: edgeCommitPackageSet,
 			containerPkgsKey: func(t *imageType) rpmmd.PackageSet {
 				return rpmmd.PackageSet{
-					Include: []string{"nginx"},
+					Include: []string{"nginx"}, // FIXME: this has no effect
 				}
 			},
 		},

internal/image/ostree_container.go

@@ -22,7 +22,7 @@ type OSTreeContainer struct {
 	OSTreeRef              string
 	OSTreeParent           *ostree.CommitSpec
 	OSVersion              string
-	ExtraContainerPackages rpmmd.PackageSet
+	ExtraContainerPackages rpmmd.PackageSet // FIXME: this is never read
 	ContainerLanguage      string
 	Filename               string
 }

internal/manifest/commit_server_tree.go

@@ -60,6 +60,7 @@ func NewOSTreeCommitServer(m *Manifest,
 }
 
 func (p *OSTreeCommitServer) getPackageSetChain() []rpmmd.PackageSet {
+	// FIXME: container package is defined here
 	packages := []string{"nginx"}
 	return []rpmmd.PackageSet{
 		{