Markhoeber/documentation/stud 1260

See draft documentation at:  http://draft-nested-components.readthedocs.org/en/latest/organizing_course.html#nested-components
Can we change the focus here so that it is on making a change to the experiment, rather than on the components or groups? I'm thinking along these lines:
You can change the structure that you have selected for a content experiment. For example, you may rethink your experiment and decide that you want to compare two ways of presenting material instead of three, or compare four ways instead of two. To make this change, you change the group configuration for the content experiment first, and then you make sure that each of the groups in the new configuration has a component assigned to it. (or along those lines)