nginx related metrics documented in [1] i.e.
nginx_http_connections , nginx_error_log, openresty_shdict_capacity,
openresty_shdict_free_space, nginx_metric_errors_total need additional documentation - what these are measuring and their importance . This is to help with writing prometheus alerts.

[1] https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.4/html-single/deployment_options/index#prometheus-metrics