Manual: Update help.txt [skip CI]
Manual: Update help.txt [skip CI]

`--reuse-hazard` is a new option in the help text

Former-commit-id: f03745f1144ee19b41081e30df01dde98b97cfe0
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine