add docs about demo data* (#162)

Author: 3nids

docs/docs/configuration/demo_data.md

@@ -0,0 +1,50 @@
+# Demo Data
+
+Demo data in pum allows you to provide sample datasets that can be loaded into your database for testing, development, or demonstration purposes.
+
+## Overview
+
+Demo data is defined in your [configuration file](configuration.md) using the `demo_data` section. You basically provide an SQL file (or multiple SQL files) to fill the data. These SQL files are typically generated using `pg_dump` with specific options to export only the data you want to include.
+
+## Configuration
+
+Demo data is configured using the [`DemoDataModel`](../api/config_model.md#demodatamodel) in your `.pum.yaml` configuration file. Each demo dataset requires:
+
+- **name**: A descriptive name for the demo dataset
+- **file**: Path to a single SQL file containing the demo data
+- **files**: List of paths to multiple SQL files (use either `file` or `files`, not both)
+
+### Single File Example
+
+```yaml
+demo_data:
+  - name: some cool demo dataset
+    file: demo_data/demo_data.sql
+```
+
+### Multiple Files Example
+
+```yaml
+demo_data:
+  - name: some cool demo dataset
+    files:
+      - demo_data/demo_data_1.sql
+      - demo_data/demo_data_2.sql
+```
+
+## Creating Demo Data Files
+
+To create demo data SQL files, use `pg_dump` with the following options:
+
+```bash
+pg_dump --inserts --data-only --no-owner --no-privileges --schema=YOUR_DATA_SCHEMA > demo_data.sql
+```
+
+**Options explained:**
+- `--inserts`: Use INSERT commands instead of COPY (more portable)
+- `--data-only`: Export only data, not schema definitions
+- `--no-owner`: Don't include ownership information
+- `--no-privileges`: Don't include privilege information
+- `--schema=YOUR_DATA_SCHEMA`: Export data only from the specified schema
+
+Replace `YOUR_DATA_SCHEMA` with the name of your schema containing the demo data you want to export.

docs/mkdocs.yml

@@ -70,6 +70,7 @@ nav:
   - Application: application.md
   - Configuration:
       - Overview: configuration/configuration.md
+      - Demo data: configuration/demo_data.md
       - Models:
         - ConfigModel: configuration/models/config_model.md
         - DependencyModel: configuration/models/dependency_model.md