Use `production` branch instead `beta`

[turadg]

README should indicate how to deploy to production.

Currently it's by updating beta branch. That seems like a misnomer for the state of production psm.inter.trade. Often it's the main/master branch that gets deployed, but that's with CI qualifying it for deployment. If we develop that then we could do it. Otherwise, consider using production for the branch name.

If we continue to use a branch for deployment, we should have guidelines on qualifiying releases. A manual test script if not an automated one.

[turadg]

I documented in #25 and rescoped this to hardening the process

[turadg]

Dropping the prio of this until we sort out dapp hosting