Merge branch 'docs-postgresql-metadata' into 'master'

Docs: Update PostgreSQL-related pages with metadata

See merge request gitlab-org/gitlab!43755

doc/administration/postgresql/external.md

+---
+stage: Enablement
+group: Database
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+---
+
 # Configure GitLab using an external PostgreSQL service
 
 If you're hosting GitLab on a cloud provider, you can optionally use a

doc/administration/postgresql/index.md

 ---
+stage: Enablement
+group: Database
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 type: reference
 ---
 
 # Configuring PostgreSQL for scaling
 
 In this section, you'll be guided through configuring a PostgreSQL database to
-be used with GitLab in one of our [Scalable and Highly Available Setups](../reference_architectures/index.md).
+be used with GitLab in one of our [reference architectures](../reference_architectures/index.md).
 There are essentially three setups to choose from.
 
 ## PostgreSQL replication and failover with Omnibus GitLab **(PREMIUM ONLY)**

doc/administration/postgresql/pgbouncer.md

 ---
+stage: Enablement
+group: Database
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 type: reference
 ---
 

doc/administration/postgresql/replication_and_failover.md

+---
+stage: Enablement
+group: Database
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+---
+
 # PostgreSQL replication and failover with Omnibus GitLab **(PREMIUM ONLY)**
 
-This document will focus only on configuration supported with [GitLab Premium](https://about.gitlab.com/pricing/), using the Omnibus GitLab package.
-If you are a Community Edition or Starter user, consider using a cloud hosted solution.
-This document will not cover installations from source.
+This document focuses on configuration supported with [GitLab Premium](https://about.gitlab.com/pricing/), using the Omnibus GitLab package.
+If you're a Community Edition or Starter user, consider using a cloud hosted solution.
+This document doesn't cover installations from source.
 
-If a setup with replication and failover is not what you were looking for, see
+If a setup with replication and failover isn't what you were looking for, see
 the [database configuration document](https://docs.gitlab.com/omnibus/settings/database.html)
 for the Omnibus GitLab packages.
 

doc/administration/postgresql/standalone.md

+---
+stage: Enablement
+group: Database
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+---
+
 # Standalone PostgreSQL using Omnibus GitLab **(CORE ONLY)**
 
 If you wish to have your database service hosted separately from your GitLab
-application server(s), you can do this using the PostgreSQL binaries packaged
+application servers, you can do this using the PostgreSQL binaries packaged
 together with Omnibus GitLab. This is recommended as part of our
 [reference architecture for up to 2,000 users](../reference_architectures/2k_users.md).
 
 ## Setting it up
 
-1. SSH into the PostgreSQL server.
-1. [Download/install](https://about.gitlab.com/install/) the Omnibus GitLab
-   package you want using **steps 1 and 2** from the GitLab downloads page.
+1. SSH in to the PostgreSQL server.
+1. [Download and install](https://about.gitlab.com/install/) the Omnibus GitLab
+   package you want using *steps 1 and 2* from the GitLab downloads page.
    - Do not complete any other steps on the download page.
 1. Generate a password hash for PostgreSQL. This assumes you will use the default
    username of `gitlab` (recommended). The command will request a password