add presentations link and instructions ; add GitHub PR primer
add presentations link and instructions ; add GitHub PR primer

rstroop/nch-bootcamp,justincohler/nch-bootcamp,justincohler/nch-bootcamp,justincohler/nch-bootcamp,rstroop/nch-bootcamp,justincohler/nch-bootcamp,rstroop/nch-bootcamp,rstroop/nch-bootcamp