Update Stacks blockchain feature with Proof of Transfer

[markmhendrickson]

Is your feature request related to a problem? Please describe.
The technology page's "Stacks blockchain" feature section says we use "proof-of-work" whereas we really use "Proof of Transfer" and should be updated as such.

Describe the solution you'd like
Update line to "We use Proof of Transfer (PoX) to allow developers to strike the right balance between speed and reliability."

Additional context

[markmhendrickson]

This section is getting dropped entirely with the migration to Webflow.