cogl-path: Add documentation for the angles of cogl_path_arc
cogl-path: Add documentation for the angles of cogl_path_arc

This adds documentation for how Cogl interprets the angles given to
cogl_path_arc.

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