Add external resources.

[abbreviatedman]

I think we should keep this issue open until we're reasonably confident we have all the external resources for our current curriculum fully in here.

But we may want specific issues for specific resources or groups of resources as we think of them.

[abbreviatedman]

Things we need in there:

Cohort-specific:

• roster (in the instructor-notes branch?)
• Canvas link
• Slack link
• Zoom link

General Curriculum

• glossary of terms (or bring it into GH)

More to come!

[abbreviatedman]

The roster should, like the other things under cohort-specific, go in the cohort-specific curriculum repo.

[abbreviatedman]

The general curriculum should also have the slides, though a copy of the slides a certain cohort got should be in cohort-specific repos.