Added documentation
Added documentation


Former-commit-id: a4a2809c2811806279852227e6e17e0d09bc53bf [formerly f54a4215526fd7a031b7a8968179236554097e4d]
Former-commit-id: ed150b98c445d47a22515dbe6e5428b8d53bfecd
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine