DOC: Modify BSplineTransformInitializer comments.

Author: dr.tim.allman@gmail.com
Useful addition to the doc.

Change-Id: I5f6c2caccebf0d534ed1378dff0334abd5828d18
Merge topic 'EditDoxygen_BSplineTransformInitializer_1360860290'

c6cc779 DOC: Modify BSplineTransformInitializer comments.