docs: Improve documentation of LayoutManager
docs: Improve documentation of LayoutManager

Especially with regards to layout properties and their usage inside a
ClutterScript UI definition.

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