v2.2.1

What's Changed

• automate contract build process by @penDerGraft in #41
• docs: simplify README, add CONTRIBUTING.md, bump to v2.0.0 by @Jesse-Sawa in #44
• Update system image and point to Github's CDN in readme by @Jesse-Sawa in #45
• Change compiler version to ^0.8.4 for client-facing contracts by @Jesse-Sawa in #46

Full Changelog: v2.2.0...v2.2.1