improve docs of QSGGeometry::set[Vertex|Index]DataPattern
improve docs of QSGGeometry::set[Vertex|Index]DataPattern

Change-Id: I6ca0d8549891302cc9d71bdfac11704752caaf60
Reviewed-by: Yoann Lopes <27570619e45a2a46618012b16a29b452c478e806@digia.com>

matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,corngood/qtdeclarative,corngood/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,corngood/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,corngood/qtdeclarative,matthewvogt/qtdeclarative,corngood/qtdeclarative