Update config.py documentation
Update config.py documentation


Former-commit-id: b552d9c307f7c1ad6d6b81d135753820b7efda8a [formerly 8c35dc6e46f66cd2c6b5e781057e36321d92d9b0]
Former-commit-id: 2a952f53c07234210d2b9d86fa46d3338f0030b6
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine