Trigger pipeline after other repository is finished

I want to automatically trigger build pipelines for my web frontends whenever my custom Nginx image build pipeline is finished. In the docs I found a trigger for repositories, but I’m not quite sure if that is the right one to use. I tried it with one of my web frontends but it didn’t work.

  - web/my-nginx

Is this the right one and how do I use it? Do I need to add this to my nginx repository or my web frontend repositories?