Add What we value section

[leewujung]

This addresses #43.

• add a "What we value" section from homepage
• remove the "Open positions" section
• minor updates: spell out WGFAST

[github-actions[bot]]

🚀 Deployed on https://deploy-preview-49--uw-echospace.netlify.app

[leewujung]

I'll self-merge so we have up to date info on the website. Feel free to PR more changes to the Values page.