Document automatic upgrade to PostgreSQL 14

Postgres 14 is going to become our minimum supported version in
GitLab 17. GitLab 16.11 turns on auto-upgrade for single node installs.

Relates omnibus-gitlab#8340

doc/administration/postgresql/replication_and_failover.md

@@ -1004,14 +1004,7 @@ You can switch an exiting database cluster to use Patroni instead of repmgr with
 
 ### Upgrading PostgreSQL major version in a Patroni cluster
 
-As of GitLab 14.1, PostgreSQL 12.6 and 13.3 are both shipped with the Linux package by default. As of GitLab 15.0,
-PostgreSQL 13 is the default. If you want to upgrade to PostgreSQL 13 in versions prior to GitLab 15.0, you must ask for
-it explicitly.
-
-WARNING:
-The procedure for upgrading PostgreSQL in a Patroni cluster is different than when upgrading using repmgr.
-The following outlines the key differences and important considerations that need to be accounted for when
-upgrading PostgreSQL.
+For a list of the bundled PostgreSQL versions and the default version for each release, see the [PostgreSQL versions of the Linux package](../package_information/postgresql_versions.md).
 
 Here are a few key facts that you must consider before upgrading PostgreSQL:
 
@@ -1056,7 +1049,7 @@ Considering these, you should carefully plan your PostgreSQL upgrade:
 1. Upgrade PostgreSQL on **the leader node** and make sure that the upgrade is completed successfully:
 
    ```shell
-   sudo gitlab-ctl pg-upgrade -V 13
+   sudo gitlab-ctl pg-upgrade
    ```
 
    NOTE:
@@ -1083,7 +1076,7 @@ Considering these, you should carefully plan your PostgreSQL upgrade:
 1. Upgrade PostgreSQL **on replicas** (you can do this in parallel on all of them):
 
    ```shell
-   sudo gitlab-ctl pg-upgrade -V 13
+   sudo gitlab-ctl pg-upgrade
    ```
 
 If issues are encountered upgrading the replicas,

doc/update/versions/gitlab_16_changes.md

@@ -87,6 +87,20 @@ For more information about upgrading GitLab Helm Chart, see [the release notes f
   packaged GitLab 16.0 and later does not automatically create the directory structure.
   [Read the issue for more details and the workaround](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/8320).
 
+## 16.11.0
+
+### Linux package installations
+
+In GitLab 16.11, PostgreSQL will automatically be upgraded to 14.x except for the following cases:
+
+- You are running the database in high availability using Patroni.
+- Your database nodes are part of a GitLab Geo configuration.
+- You have specifically [opted out](https://docs.gitlab.com/omnibus/settings/database.html#opt-out-of-automatic-postgresql-upgrades) from automatically upgrading PostgreSQL.
+- You have `postgresql['version'] = 13` in your `/etc/gitlab/gitlab.rb`.
+
+Fault-tolerant and Geo installations support manual upgrades to PostgreSQL 14,
+see [Packaged PostgreSQL deployed in an HA/Geo Cluster](https://docs.gitlab.com/omnibus/settings/database.html#packaged-postgresql-deployed-in-an-hageo-cluster).
+
 ## 16.10.0
 
 ### Linux package installations