docs(howto): add how-to guide for separating models file

docs/howto/separate-models-file.md

@@ -0,0 +1,50 @@
+# Separating models file
+
+By default, sqlc uses a single package to place all the generated code. But you may want to separate
+the generated models file into another package for loose coupling purposes in your project.
+
+To do this, you can use the following configuration:
+
+```yaml
+version: "2"
+sql:
+  - engine: "postgresql"
+    queries: "queries.sql"
+    schema: "schema.sql"
+    gen:
+      go:
+        out: "internal/"  # Base directory for the generated files. You can also just use "."
+        sql_package: "pgx/v5"
+        package: "sqlcrepo"
+        output_batch_file_name: "db/sqlcrepo/batch.go"
+        output_db_file_name: "db/sqlcrepo/db.go"
+        output_querier_file_name: "db/sqlcrepo/querier.go"
+        output_copyfrom_file_name: "db/sqlcrepo/copyfrom.go"
+        output_query_files_directory: "db/sqlcrepo/"
+        output_models_file_name: "business/entities/models.go"
+        output_models_package: "entities"
+        models_package_import_path: "example.com/project/module-path/internal/business/entities"
+```
+
+This configuration will generate files in the `internal/db/sqlcrepo` directory with `sqlcrepo`
+package name, except for the models file which will be generated in the `internal/business/entities`
+directory. The generated models file will use the package name `entities` and it will be imported in
+the other generated files using the given
+`"example.com/project/module-path/internal/business/entities"` import path when needed.
+
+The generated files will look like this:
+
+```
+my-app/
+├── internal/
+│   ├── db/
+│   │   └── sqlcrepo/
+│   │       ├── db.go
+│   │       └── queries.sql.go
+│   └── business/
+│       └── entities/
+│           └── models.go
+├── queries.sql
+├── schema.sql
+└── sqlc.yaml
+```

docs/index.rst

@@ -66,6 +66,7 @@ code ever again.
    howto/embedding.md
    howto/overrides.md
    howto/rename.md
+   howto/separate-models-file.md
 
 .. toctree::
    :maxdepth: 3