[e.cash] Build page updates

Summary:
Proposed improvments to /build page style and maintainablity

• Moving some copy from the top section below the fold as was a lot and causing overflow issues
• Styling the links a bit more
• Move the info to an array and mapping over it instead to easily add or remove items

Test Plan: Preview the site and check /build

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Subscribers: bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D15994