chore(docs): add documentation about which files/data should be back up (#1254)

* chore(docs): add documentation about which files/data should be back up

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: backups category.json

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: postgresql documentation

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: database backup command

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: moved backup to a single page

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: postgresql options (replace dbname by port)

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: remove lost+lost folder

---------

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

docs/using-jellyseerr/backups.md

@@ -0,0 +1,93 @@
+---
+title: Backups
+description: Understand which data you should back up.
+sidebar_position: 4
+---
+
+# Which data does Jellyseerr save and where?
+
+## Settings  
+
+All configurations from the **Settings** panel in the Jellyseerr web UI are saved, including integrations with Radarr, Sonarr, Jellyfin, Plex, and notification settings.  
+These settings are stored in the `settings.json` file located in the Jellyseerr data folder.
+
+## User Data  
+
+Apart from the settings, all other data—including user accounts, media requests, blacklist etc. are stored in the database (either SQLite or PostgreSQL).
+
+# Backup
+
+### SQLite
+
+If your backup system uses filesystem snapshots (such as Kubernetes with Volsync), you can directly back up the Jellyseerr data folder.  
+Otherwise, you need to stop the Jellyseerr application and back up the `config` folder.
+
+For advanced users, it's possible to back up the database without stopping the application by using the [SQLite CLI](https://www.sqlite.org/download.html). Run the following command to create a backup:  
+
+```bash
+sqlite3 db/db.sqlite3 ".backup '/tmp/jellyseerr_db.sqlite3.bak'"
+```  
+
+Then, copy the `/tmp/jellyseerr_dump.sqlite3.bak` file to your desired backup location.
+
+### PostgreSQL
+
+You can back up the `config` folder and dump the PostgreSQL database without stopping the Jellyseerr application.
+
+Install [postgresql-client](https://www.postgresql.org/download/) and run the following command to create a backup (just replace the placeholders):
+
+:::info
+Depending on how your PostgreSQL instance is configured, you may need to add these options to the command below.
+
+  -h, --host=HOSTNAME      database server host or socket directory
+
+  -p, --port=PORT          database server port number
+:::
+
+```bash
+pg_dump -U <database_user> -d <database_name> -f /tmp/jellyseerr_db.sql
+```
+
+# Restore
+
+### SQLite
+
+After restoring your `db/db.sqlite3` file and, optionally, the `settings.json` file, the `config` folder structure should look like this:
+
+```
+.
+├── cache            <-- Optional
+├── db
+│   └── db.sqlite3
+├── logs             <-- Optional
+└── settings.json    <-- Optional (required if you want to avoid reconfiguring Jellyseerr)
+```
+
+Once the files are restored, start the Jellyseerr application.
+
+### PostgreSQL
+
+Install the [PostgreSQL client](https://www.postgresql.org/download/) and restore the PostgreSQL database using the following command (replace the placeholders accordingly):
+
+:::info
+Depending on how your PostgreSQL instance is configured, you may need to add these options to the command below.
+
+  -h, --host=HOSTNAME      database server host or socket directory
+
+  -p, --port=PORT          database server port number
+:::
+
+```bash
+pg_restore -U <database_user> -d <database_name> /tmp/jellyseerr_db.sql
+```
+
+Optionally, restore the `settings.json` file. The `config` folder structure should look like this:
+
+```
+.
+├── cache            <-- Optional
+├── logs             <-- Optional
+└── settings.json    <-- Optional (required if you want to avoid reconfiguring Jellyseerr)
+```
+
+Once the database and files are restored, start the Jellyseerr application.