FCX docs

Documents in docs/ of the Zeus repo. Reachable only while connected to Twingate.

Specifications

• FCX FIX Specification v1.0.0Market data and order entry gateways. Provisional; decisions in FCX-183.
• FCX FIX Specification changelogChanges to the FIX spec, by version. Keep a Changelog format.

The FIX spec is also on Confluence, generated from fix-spec.html.