* CORDA-3193: Update docs to mention branching strategy
Removed mention of master branch except to describe that the master branch is no longer used.
Added explanation of branching strategy to contributing guide.
Renamed building-against-master to building-against-non-release
* CORDA-3193: Update docs to mention branching strategy
Updated contributing document to mention that work should go into the default branch by default.
* CORDA-3193: Update docs to mention branching strategy
Removed unnecessary backtick.
* CORDA-3193: Updated contributing section
Corrected term from "current development branch" to "equivalent branch"
