Should deploy when changes in gazebosim/docs are merged

[azeey]

Currently changes made to https://github.com/gazebosim/docs are not reflected on the website until we manually re-deploy this backend. It would be nice if gazebosim/docs can trigger a deploy. One possibility is to use trigger the workflow_dispatch event via curl (see https://github.com/orgs/community/discussions/26323#discussioncomment-3251448), but it's not clear if that works on private repos.

Alternatively, we could upload the contents of gazebosim/docs to S3 from that repo instead of cloning it in the backend.