Update screenshots on the `coderit.org/hackathon-manager` website

[peterkos]

Screenshots need to be updated for 2.0
Ideally done by 2.1 but oh well, #notabreakingchange

[peterkos]

Add instructions for running website @me

[cbaudouinjr]

Blocked: I'd like to get the sidebar changes fixed before we take any screenshots.

[peterkos]

Still blocked; one more sidebar fix to go! #481
(This also means we can get stuff like Legal Agreements showcased. Woo!)