demos/risk/Scenario/README.txt:
demos/risk/Scenario/README.txt:

Added a brief README for the Scenario risk demo pack.


Former-commit-id: 243ca4033b30fabe1ef0d7e389014cadd76f6657
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine