calcs/hazard/classical/__init__:
calcs/hazard/classical/__init__:

Added notes about SMLT and GSIMLT paths. Also added a brief explanation
of hazard curve grouping.


Former-commit-id: 694fa2b3a0e9e371a7a3f41e640ea5ba95adb62e
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine