OpenQuake Engine 2.0 doc: add development
OpenQuake Engine 2.0 doc: add development


Former-commit-id: 4f4e4e9330d861eda879898c0f64b8f712f44462 [formerly eeb508b73f120b9743daf37f0ce6d751ec655548]
Former-commit-id: 80c04281f52bea4b42b2c5bbf2bc85aca5e2dfd5
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine