cookbook: Remove the note about indenting <xi:include>
cookbook: Remove the note about indenting <xi:include>

It's not necessary now to special case the indentation of includes as
the XSLT for the cookbook strips leading and trailing space automaticaly
for us.

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