Where do people recommend logging infrastructure changes (e.g. database changes, server configuration) for all things potentially not in code?
What you should use depends on what tools you have available. We currently use Datadog, so we use their API for publishing events. We can then search for them in the event stream or overlay them on dashboards.
You could look at the datastores Grafana supports for annotations and choose whichever of them you're comfortable operating.
One example - https://github.com/joelparkerhenderson/architecture_decision...