Align the guide with external-module-framework-docs

[pbchase]

Vandy's VICTR is about to merge the EM Guides exercises into their public external-module-framework-docs, specifically, this is happening in the merge-UofF-guide branch. We should remove the exercises replacing them with links to the Vandy EM Docs when vanderbilt-redcap/external-module-framework-docs#2 is merged.

We might be well-served to put each of our remaining documents in the left sidebar to promote their utility to people that find us via links from Vandy. This was @ChemiKyle's idea.