Cleanup chapter overviews

[profvjreddi]

Currently, each chapter has a little bit of a paragraph before getting into the overview, and this seems a little redundant. I should clean this up so that the whole thing reads a bit tighter because sometimes we tend to repeat the things being said.

[profvjreddi]

The start could focus on the "purpose of the chapter" and then we go into Learning objectives and then the introduction/overview of the chapter.