cookbook: Minor modification to wording to improve clarity
cookbook: Minor modification to wording to improve clarity

Text referred to three animation methods, but only provides
examples for two of them; and in future there may be more/fewer
than 3. So I reworded it.

Distrotech/clutter,Distrotech/clutter,kerrickstaley/clutter-vala,GNOME/clutter,djdeath/clutter-multithreaded,djdeath/clutter-android,heysion/clutter-clone,collects/clutter,djdeath/clutter-multithreaded,jigpu/clutter,nobled/clutter,kerrickstaley/clutter-vala,djdeath/clutter-android,djdeath/clutter-android,djdeath/clutter,ebassi/clutter,GNOME/clutter,Distrotech/clutter,rkudiyarov/clutter_osx,spatulasnout/clutter,GNOME/clutter,jigpu/clutter,djdeath/clutter,Distrotech/clutter,heysion/clutter-clone,rkudiyarov/clutter_osx,djdeath/clutter-multithreaded,heysion/clutter-clone,spatulasnout/clutter,collects/clutter,jigpu/clutter,ebassi/clutter,nobled/clutter,Distrotech/clutter,heysion/clutter-clone,nobled/clutter,djdeath/clutter,ebassi/clutter,djdeath/clutter,spatulasnout/clutter,ebassi/clutter,jigpu/clutter,dlespiau/clutter,GNOME/clutter,dlespiau/clutter,djdeath/clutter-android,djdeath/clutter-multithreaded,jigpu/clutter,GNOME/clutter,djdeath/clutter,kerrickstaley/clutter-vala,spatulasnout/clutter,dlespiau/clutter,spatulasnout/clutter,collects/clutter,jigpu/clutter,rkudiyarov/clutter_osx,Distrotech/clutter,collects/clutter,ebassi/clutter,heysion/clutter-clone,djdeath/clutter-android,rkudiyarov/clutter_osx,djdeath/clutter,kerrickstaley/clutter-vala,collects/clutter