Missing crucial step in Geo Disaster Recovery docs

Here is a link to the docs.

Step 3 does not have any specifics on what to do. https://gitlab.com/help/gitlab-geo/disaster-recovery.md

Removing the lines from gitlab.rb that placed it in read-only mode and running reconfigure yields the following error:

Error executing action `run` on resource 'execute[create gitlab database user]'

I asked @brodock and @dblessing in Slack and neither of them knew off the top of their head how to do this in Omnibus, which was kind of concerning because those would be the first people I call if a client was struggling with this. And I would imagine the client seeing it as ULTRA urgent.

/cc @stanhu