Follow-up from "Fix caps and backticks in various docs (/admin, /user)"

The following discussions from !20813 (merged) should be addressed:

• @eread started a discussion:

  - Errors like this in the `production/sidekiq` log; see: [Set default_transaction_isolation into read committed](https://docs.gitlab.com/omnibus/settings/database.html#set-default_transaction_isolation-into-read-committed)

  Based on: https://docs.gitlab.com/omnibus/settings/database.html#set-default_transaction_isolation-into-read-committed.

• @eread started a discussion:

  GitLab has support for automatically detecting and monitoring the Kubernetes NGINX Ingress controller. This is provided by leveraging the built-in Prometheus metrics included with Kubernetes NGINX Ingress controller [version 0.16.0](https://github.com/kubernetes/ingress-nginx/blob/master/Changelog.md#0160) onward.