WIP:  Content Experiments Documentation

See draft documentation at:  http://draft-nested-components.readthedocs.org/en/latest/organizing_course.html#nested-components
Rather than linking this way (which creates awkward capitals in the sentence), use the style in the formatting cheat sheet:

To cross-reference a topic, but use your own text instead of the topic title, use the :ref: directive, but enter your own text followed by the topic anchor in angle brackets:

`Add the tool as a :ref:'custom JavaScript problem<Custom JavaScript>'`