examples/layout-manager: Improve the example
examples/layout-manager: Improve the example

Add an explicit transition, and more comments.

GNOME/clutter,Distrotech/clutter,heysion/clutter-clone,heysion/clutter-clone,djdeath/clutter-android,djdeath/clutter-android,ebassi/clutter,jigpu/clutter,collects/clutter,GNOME/clutter,djdeath/clutter-android,djdeath/clutter,jigpu/clutter,Distrotech/clutter,ebassi/clutter,djdeath/clutter,collects/clutter,djdeath/clutter,ebassi/clutter,collects/clutter,heysion/clutter-clone,collects/clutter,heysion/clutter-clone,Distrotech/clutter,jigpu/clutter,djdeath/clutter,djdeath/clutter-android,Distrotech/clutter,Distrotech/clutter,GNOME/clutter,jigpu/clutter,collects/clutter,djdeath/clutter,ebassi/clutter,djdeath/clutter-android,djdeath/clutter,heysion/clutter-clone,jigpu/clutter,GNOME/clutter,ebassi/clutter,jigpu/clutter,Distrotech/clutter,GNOME/clutter