doc: Update the field standardization doc to reflect best practice

Update the field standardization doc to reflect the best practice to run, and add the logging field validator to the CI.

The update in the document follows the experience of adding the job to multiple Go services:

• Add logging field validator CI job (gitaly!8607 - merged)
• Add logging field validator CI job (gitlab-shell!1402 - merged)
• Add logging field validator CI job (gitlab-runner!6580 - merged)
• Add logging field validator CI job for Workhorse (gitlab!229835 - merged)

Related to Implement field validator in labkit-go (gitlab-org/quality/quality-engineering/team-tasks#4110 - closed).