stack-child: fix a typo in the documentation
stack-child: fix a typo in the documentation

pwithnall/mx,clutter-project/mx,pwithnall/mx,pwithnall/mx,jonnylamb/mx,jonnylamb/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,clutter-project/mx