This adds a "Reviews and Comments" page for the "Basic concepts" section

of the User Guide. This page covers what a review is, how it's created

and managed, and the different components of a review. It goes into each

type of comment (adding new documentation on General Comments in the

meantime) and links to different sections to learn more.

Built the docs. Didn't see any errors.
Checked for spelling errors.
Verified that other docs could now reference the General Comments section.