Minor spelling issue in installation script

[meglio (Anton)]

Installing a fresh Discourse instance. It looks like some file path or domain name is missing:

[mpalmer (Matt Palmer)]

Looks like it was broken by https://github.com/discourse/discourse_docker/commit/f5cf127dd84f3b9646f63c4091302df94725673f. PR welcome!

[pfaffman (Jay Pfaffman)]

I’m on it. I’ll add it to my list.