Update docs/configuring-playbook-postgres-backup.md: replace the instruction with the reference to the document copied to the MASH project

This follows the change for docs on BorgBackup with 414445b6bf.

The document on the MASH project is available at https://github.com/mother-of-all-self-hosting/ansible-role-postgres-backup/blob/main/docs/configuring-postgres-backup.md.

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-playbook-postgres-backup.md

@@ -10,41 +10,8 @@ SPDX-License-Identifier: AGPL-3.0-or-later
 
 The playbook can install and configure [docker-postgres-backup-local](https://github.com/prodrigestivill/docker-postgres-backup-local) for you via the [ansible-role-postgres-backup](https://github.com/mother-of-all-self-hosting/ansible-role-postgres-backup) Ansible role.
 
-For a more complete backup solution (one that includes not only Postgres, but also other configuration/data files), you may wish to look into [BorgBackup](configuring-playbook-backup-borg.md) instead.
+For details about configuring and installing it, you can check them via:
+- [the role's document on the MASH (mother-of-all-self-hosting) project](https://github.com/mother-of-all-self-hosting/ansible-role-postgres-backup/blob/main/docs/configuring-postgres-backup.md)
+- `roles/galaxy/postgres_backup/docs/configuring-postgres-backup.md` locally, if you have fetched the Ansible roles
 
-## Adjusting the playbook configuration
-
-To enable Postgres backup, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
-
-```yaml
-postgres_backup_enabled: true
-```
-
-Refer to the table below for additional configuration variables and their default values.
-
-| Name                              | Default value                | Description                                                      |
-| :-------------------------------- | :--------------------------- | :--------------------------------------------------------------- |
-|`postgres_backup_enabled`|`false`|Set to true to use [docker-postgres-backup-local](https://github.com/prodrigestivill/docker-postgres-backup-local) to create automatic database backups|
-|`postgres_backup_schedule`| `'@daily'` |Cron-schedule specifying the interval between postgres backups.|
-|`postgres_backup_keep_days`|`7`|Number of daily backups to keep|
-|`postgres_backup_keep_weeks`|`4`|Number of weekly backups to keep|
-|`postgres_backup_keep_months`|`12`|Number of monthly backups to keep|
-|`postgres_backup_base_path` | `"{{ matrix_base_data_path }}/postgres-backup"` | Base path for postgres-backup. Also see `postgres_backup_data_path` |
-|`postgres_backup_data_path` | `"{{ postgres_backup_base_path }}/data"` | Storage path for postgres-backup database backups |
-
-## Installing
-
-After configuring the playbook, run it with [playbook tags](playbook-tags.md) as below:
-
-<!-- NOTE: let this conservative command run (instead of install-all) to make it clear that failure of the command means something is clearly broken. -->
-```sh
-ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start
-```
-
-The shortcut commands with the [`just` program](just.md) are also available: `just install-all` or `just setup-all`
-
-`just install-all` is useful for maintaining your setup quickly ([2x-5x faster](../CHANGELOG.md#2x-5x-performance-improvements-in-playbook-runtime) than `just setup-all`) when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just setup-all`, or these components will still remain installed. Note these shortcuts run the `ensure-matrix-users-created` tag too.
-
-## Troubleshooting
-
-As with all other services, you can find the logs in [systemd-journald](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html) by logging in to the server with SSH and running `journalctl -fu matrix-postgres-backup`.
+**Note**: for a more complete backup solution (one that includes not only Postgres, but also other configuration/data files), you may wish to look into [BorgBackup](configuring-playbook-backup-borg.md) instead.