Merge branch 'add-postgresql-versions-docs' into 'master'

Add new PostgreSQL versions

See merge request gitlab-org/omnibus-gitlab!4570

doc/package-information/postgresql_versions.md

@@ -15,6 +15,7 @@ Read more about update policies and warnings in the PostgreSQL
 | GitLab version | PostgreSQL versions | Default version for fresh installs | Default version for upgrades | Notes |
 | -------------- | --------------------- | ---------------------------------- | ---------------------------- | ----- |
+| 13.4 | 11.9, 12.4 | 11.9 | 11.9 | Package upgrades aborted if users not running PostgreSQL 11 already |
 | 13.3 | 11.7, 12.3 | 11.7 | 11.7 | Package upgrades aborted if users not running PostgreSQL 11 already |
 | 13.0 | 11.7 | 11.7 | 11.7 | Package upgrades aborted if users not running PostgreSQL 11 already |
 | 12.10 | 9.6.17, 10.12, and 11.7 | 11.7 | 11.7 | Package upgrades automatically performed PostgreSQL upgrade for nodes that are not part of a Geo or repmgr cluster. |