wiki: fix a copy/paste typo
wiki: fix a copy/paste typo

Former-commit-id: d30ba0bde4afeeb4fb95d203b9865d38ed0f59d8 [formerly 8f3a49e2b63f042bf70f1505382c5fdf7a310375]
Former-commit-id: cb64bda56d46c29220e4c948a7ebf0c1f511a25c
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine