Update 00_URSC645_AnnotatedBibliography.md

[nmg87-tamu]

Summary

Edited Gentzkow and Shaprio to be slightly shorter, also reformatted some previous inconsistencies. Also added some definitions that were previously left unentered

List of changes proposed in this PR (pull-request)

• Edited Gentzkow and Shaprio.
• Entered new definitions.
• Reformatted some issues primarily around each chapters key words section.
• Removed unnecessary information to reduce overall length.

What should a reviewer concentrate their feedback on?

• [x] Gentzkow and Shapiro
• [x] Everything looks ok?

Acknowledging contributors

• [ ] All contributors to this pull request are already named in the table of contributors in the README file.
• [ ] The following people should be added to the table of contributors in the README file:

[npr99]

A worthy effort to trim down the entry. Good job figuring out how to make a pull request and working with markdown.