Add codename to the README.md
Add codename to the README.md


Former-commit-id: 9bdf9c5ec503a3c1a750a307e92434f4cbbdf2dd [formerly c9baea19908aabcd43307ff44fb16c8edd48a28e]
Former-commit-id: 3a42d9a1f17ce7246f43fe2d7afb0efe8eebc551
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine